[Poll] Need help with choosing which game to buy

my wishlist

Then buy one game you want to play right now.

I spent 581 hours with Grim Dawn. It's not hard to guess which game I voted for :D

Which of these games would you buy first, if you could choose just one?

Assuming you mean, which would I buy for myself, and we're working off the premise that I'm playing these for the first time, then Icewind Dale (which, incidentally, is one of only three games I've ever pre-ordered- and, along with Life is Strange, one of the two I haven't at all regretted doing so for): (The third game, NWN, was a disaster on launch, and while fan content and core updates and expansions finally redeemed the game, that was years later, making the launch purchase a complete waste.)
No other game (other than the delightful yet console-exclusive Baldur's Gate: Dark Alliance/Champions of Norrath games) has captured the thrill and challenge of tabletop dungeon exploring within an action-RPG format quite like Icewind Dale. Certainly, a number of turn-based games have managed it, but among action RPGs, there are only those select few. Moreover, all of the games mentioned are vastly improved by co-op [while, conversely, many other D&D digital games with co-op aren't really suited for it, due to their party-centric play; meanwhile Icewind Dale plays best with only a character or two under your control (being more similar to NWN than Baldur's Gate in that regard) and relies heavily on teamwork play].

On the other hand, If you mean 'which would I buy for myself now', then Grim Dawn, Firewatch, or Underail, depending on which itch I needed to scratch (though Darkest Dungeon's base game'd be an easy top to that list; on the other hand, its DLCs seem pretty disfavorable).

Finally, if you mean 'which would I recommend to someone else', then Planescape: Torment, hands down. While I haven't played many newer isometric RPGs (including any of Obsidian's games), among classic games only Temple of Elemental Evil, the first two Fallouts, and the Dark Sun games compare to P:T in terms of setting richness.
As far as those go, the FT games feel a bit flat and dated (and have story and mechanic elements that make the games hard to take very seriously), ToEE has limited story involvement and a specific emphasis on dungeon-crawling that further detracts from building story depth (and is mostly notable for its VTMB-like adjustment of dialogue based on your party alignment and stats, giving it decent replayability), and the Dark Sun games are inherently amazing, but are ruined by also being a broken bugfest.
They're all worth playing, but P:T not only tops them on basic marks (other than for art, which ToEE easily beats it out in), it has the benefit of taking place in the delicious Planescape [AKA Blood Wars] setting, which is really the most engaging and unique D&D-derived setting out there (as far as gaming goes; as far as reading goes, Dragonlance is the most involved offering available).

tl;dr version: Planescape and Icewind Dale are fantastic, while Grim Dawn and Firewatch and Underrail all look very good.

bg2

Bump. Definitely Full Throttle Remastered.

I would choose Baldurs Gate 2 without mods if it is your first play, BG 2 with mods or
Baldur's Gate: Siege of Dragonspear if you already played/finished once BG 2.
Voted Baldur's Gate: Siege of Dragonspear.