Help Me Pick Which RPG To Play Next

Grimrock and don't look back
if you like it, track down Wizardry 7, which is the pinnacle of the genre. you should be able to trade it for just a few refs/cards

id' pick grimrock 2.

fallout 1 is boring, wasteland 2 is pretty shallow and repetitive, and underrail is terribly unbalanced (and also the rng seems to be fixed against you).

don't know about the rest.

You can't go wrong with Fallout 1.

If Grimrock 2 is like Grimrock 1 that's a solid choice.

If you want more suggestions, there's Shadowrun Returns/Dragonfall/Hong Kong.

I tried Wasteland 2: Director's Cut in the free weekend and I think it is pretty decent.

If you dont wanna play on steam find a copy of Chrono Trigger best rpg i have played

How about Pillars of Eternity? It's on the new HB monthly. Friend of mine game me a copy yesterday and it's really not bad.

Renowned Explorers is really really good. Recommend it with all my heart. The community's great and run weekly challenges so the game doesn't get boring.

LOG 2 is a fine update to the dungeon-crawling genre. I sort of quit playing it though, after gog.com got the legendary SSI "Gold Box" D&D games like Eye of the Beholder xD.

I voted for Wasteland 2 since it is a great game and played it many times.

View attached image.

Fallout 1, if you're looking for a not-so-simple-to-grasp game that deviates from the industry norm. The narrative blows modern RPGs out of the water with its depth and ability to immerse you into the world.
The sheer amount of things you can do and the resulting things that can occur is overwhelming - in traditional older-gen game form, it sacrifices ease of play-ability and mass-market appeal for a dive into complex traditional RP game-style gameplay, alongside a story wrapped around the persevering spirit of mankind even after the apocalypse.
The gameplay is still there, albeit aged - you stil have V.A.T.S, but SPECIALS and perks interact differently: for instance, you have to be smart enough to see that you can utilize your speech skill to persuade a person, as opposed to the shitty RNG system in FO 3.

It's arguably one of the greatest RPGs ever made, up there with its successor(FO 2), Planescape Torment, Chrono Trigger, etc.

Is Fallout thinking of the children, though...

is that a real thing? did they really kill off the children? I like funny lines and dislike removed content personally

edit: I think Grimrock 2 would take the least effort, time and commitment to play and finish. Or maybe Renowned Explorers: International Society would too, but I have no idea about that game. I think most of these games look fairly long depending how you play, though.

Dragon Age: Origins is something you must play if you like modern turn-based RPGs, we may consider the pause-based combat system its evolution. I see you have it in you library but you got 0 hrs. Another similar game is Aarklash: Legacy, you can change the skill-tree of the characters at any time ad you have a limited amount of items to equip (4 if I remember correctly), making the pause-based combat the main focus of the gameplay. Both games are pretty challenging even on normal difficulty.

Otherwise, from you list, Legend of Grimrock 2 is great if you like the genre, Divine Divinity is a lot of fun if you don't mind playing (very) old games but it isn't turn-base, Fallout also great being so old, and I got Wasteland 2 on my wishlist.

Zenith

Age of Decadence, to actually say something out of the norm. It is nicely overtly overcomplicated and quite relentless to separate the wheat from the chaff.
Also, Xenonauts is not an RPG, it is a turn-based tactical game.

Fallout 1 & 2 as long as you don´t heavily dislike post-apocalypse.

From that list I only played Wasteland 2 and Underrail. Wasteland 2 is okay. It is pretty long and polished but there are certain skills you need as usual and often there is some kind of prefered solution to quests as you are a Ranger. If you like playing the good guy it is recommendable.

Underrail I found pretty interesting. Well, first off. I only played the game during Early Access so I don't know how relevant my information are at all :P. I did two playthroughs back then. First I did some kind of normal gun character with the normal XP system. And the game was pretty hard. There were moments where I've chosen the violent way in order to get more Xp. Also near the end scene back then I couldn't solve a situation like I wanted as I missed some kind of skill.
On my second playthrough I've chosen the oddity Xp system which is really good and nice as it gives you more freedom on solving situations without the fear of losing experience. I played a scientist without weapon skills but with psi powers. That run was a lot easier for different reasons. And it was also a lot more fun as I could do more stuff. But yea, if you make some bad choice on character creation it may hurt your experience. But there are definetely different viable builds even exotic ones. If you like experimenting it may be something for you.

Finally i can see some fallout love!! Was so happy seeing that most votes already went for fallout when i voted XD

Usually when i recommend Fallout (1-2, the proper fallouts) i add a bunch of ifs and 'keep in mind'; But from your post its completely unecessary- Divinity Original Sin and its irk they all drink from this fountain called Fallout.

About the others for comparison:

Age o Decadence is a extremely fallout inspired on bronze age of sorts and approved for that- but a way lower game overall. Its like a loveletter that is a good loveletter but shys in comparison to the source on every aspect.

UnderRail and Wasteland 2 are like Age of Decadence but better- still not as good as Fallou 1-2.
PS: Wasteland 2 follows the plot from Wasteland 1 but its way closer to Fallout and Fallout Tactics. Fallout btw was heavily inspired by wasteland 1. Sadly wasteland 2 didn't captured the spirit of wasteland 1(just the plotline) and while its pretty good it doesn't compare to fallout 1-2 (we're talking classics here).

Massive Chalice, Xenonauts and Renowed Explorers are more akin to PvP turn-based games then singleplayer story-centered tb rpgs. Each is very different from one another but they're all more arcadey so to say, almost like a board game. Each turn-based encounter feels more like a isolated level.
They compare more to x-com then Fallout/Divinity.

Thea is freaking awesome but its a whole other beast. Its a kind of 4x strategy rogue-like with rpg-like encounters (little stories) and a completely different kind of turn-based combat around cards. There is no tactical grid battle and such.

Avernum and Grimrock while different are more of dungeon crawlers. Divinity is full of dungeons so they may be up to your liking (and they're good) but won't be as on spot to the kind of experience you enjoyed with Divinity. Avernum gets closer but its inspirations are more oldschool... heck id paint it closer to rogue (you know, the game that created the rogue-like genre) but with story then a story with turn-based mechanics.

And finally other Divinitys...
They're good.
But each divinity is a different kind of gameplay. Divinity is a diablo clone. Divinity 2 (not Original Sin) is a third person action rpg (some pretty unique ideas and kind of a underprectiated gem)... and Divinity Dragon Comander is a whole other beast of RTS with card collectibles and visual novel like relationships with rpg story choices (yeah, its weird like that and a lovely chimera that somehow works).

I recommend all of those, reserving just some ifs with Grimrock, Age o Decadence and Divine Divinity - those need a much more particular kind of niche fanhood to be enjoyed. If i were you i would wishlist any and all of those that clicked closer to you.

But the definite recommendation Must Play that you will certainly like is Fallout.
They're not clasics(2 included) just because of their age or their relevance at the time. They're well regarded as masterpieces on gaming and conerstones of the Rpg genre- plus they're still the main source from wich pretty much every turn-based rpg draws from and look up to be.
Heck: before complex storylines and wild options like marriage became a thing in sandbox and modern rpgs Fallout was the game that did this, in a time rpgs were all about save the world from doom entering dungeons and collect-me 30 goblin ears.
And to this day theres more complex storylines there with more ways of solving and different outcomes then... anything yet? Yep. I recall like 1 quest from fallout 3 being close to the amount of different ways each 'quest'/interaction can be done in fallout. Fgs i recall people a in a fallout-fans forum still discovering unexpected surprises or secrets years after the game launch (wikis made things easier so i guess now all was uncovered).
I mean... come on: you open a water pool in the middle of the town where you can get water. Like all containers in the game where you get things you can leave things... if you leave some rotten radiated meat there you will find out days later pretty much everyone died of poisoning.
Is that a plotline? Hinted at by some npc marked on you quest log?
NADA. Its just... how the world of fallout works.

I am biased. I was a dedicated fan, was active in a number of fan forums (pre-steam age), helped translating it to pt-br. Heck i self-taught myself english playing rpgs and started/learned the most from Fallouts- its the game that made me start getting serious about learning it, doing it with dictionaire on the side.
But anytime i rationally look into it -to hell, this ain't just nostalgia glasses. They are masterpieces.

DO KEEP IN MIND:
-They're old and it shows, little animations and rough edges... use community patches for bugs and better resolution.
-Fallout 1 is kinda short for a rpg and runs on a timer.
Like, really. You have 13 in-game days to fix the Vault's water chip. You can find ways to extend that time in the game but not by much.
It does make for some amazing playthroughs and its really awesome the different paths you can take - but it can lead to some failed savefiles (like, a point where you won't fix the chip no matter how fast you hurry so better restart) and its smaller in pretty much every aspect compared to Fallout 2. However it does have a more cohesive plot line while Fallout 2 indulges in more humor and some random encounters that are trully, trully random (like finding Doctor Who's police box just left in the waste). They're rare but they're there, won't spoil much (like really rare- it took me years in multiple playthroughs to see them all myself).
-They have bugs. Community patches please.
But nothing close to how bethesda release games.

PS(edit):
The soundtrack. The motherf&#% ambient soundtrack from fallout 1-2... it gives me the shivers to this day.
Its a rare kind of ambience music few games do and fewer do well. Making tracks that blend without distracting(ambient) while at the same time becoming so recognbizeable and memorable is some kind of feat that needed a award in music. Even ambient artits i enjoy, most just some tracks hits the nail and few albums are entirely that good.

Either fallout or wasteland 2.

Have you played skyrim/oblivion or any Witcher game? I highly recommend these to anyone who enjoys RPGs.

P.s. Everyone knows the Witcher 3, but there is 2 other GREAT game in the series.
P.P.s. Vanilla Skyrim is fun, but mods make it great (Any there is PLENTY of good ones on the nexus)

voted for fallout, best classic. you could also play baldurs gate 2 or neverwinter 1, 2 and addons if you didn't yet.

Clearly not the popular choice, but I adore Renowned Explorers, just such a fun rogue like game. I will say there is not nearly enough to do in it, after 7 or 8 play throughs, I had little interest in returning just to skip through all the scenes I've already seen. So if you start it, be prepared to need something new in a week or two. I can say Massive Chalice is quite fun too, Wasteland 2 seems amazing... but I have not gotten myself to really get into it, barely started lol so I can't attest to it really. I have played a few of the others, but none that I truly enjoyed, and I obviously can't comment on those I've never played at all.