Multiplayer FPS games

In this thread, we talk about multiplayer FPS games and our opinions and experiences with them. Maybe even compare them. I'll start off.

Blacklight: Retribution - I started playing this few days ago and I like it very much so far. Doesn't seem like pay to win and getting everything you want takes a bit of grinding, but nothing too severe. If you just play not thinking about it, it will come sooner than you'd expect (or so I hear).
Borderlands - Gets boring really fast when playing solo, but I can play it literally 8-10 hours a day with friends on Skype. It has decent replay value if you're into leveling all 4 classes. I'm personally interested only in hunter and siren so that's easily 100-150 hours of gameplay.
Borderlands 2 - I own it, but I haven't played it yet. I hear it fixed most things that were bad about the first game.
Call Of Duty franchise - The last COD games I player were COD1 and COD2. From what I hear, last good installment was COD4 and from there everything went downhill. Community is absolutely horrible and the games are very dumbed down. I have to admit, though, Black Ops 2 looks fun if you play with proper people.
Counter-Strike 1.6 - I used to play CS back in elementary school when 1.5 was new. I played it with classmates in LAN. The game is so old it seems like everyone had enough time to become godlike at it so it's not very friendly towards new players.
Counter-Strike: Global Offensive - Much more friendly towards new players when compared to 1.6. I bought it on release, but haven't given it much attention because I was focused on other games. Looks promising.
Day Of Defeat: Source - Most people seem to have forgotten about this game, but it's very good. I see it as cross between CS (realism) and TF2 (teams and classes).
Killing Floor - Excellent team game with ridiculous replay value if you don't mind dated graphics.
Left 4 Dead 2 - Most people compare it to KF, but their only similarities are being team based and shooting things. It's also excellent, but requires friends to be fun because community is pretty bad.
Natural Selection 2 - The most team oriented game I've played to this date. If your CPU can handle it, you'll have tons of fun. My current main game, along with BLR. It has a steep learning curve, but if you can handle rough beginning, you're in for quite a ride. Winning feels very rewarding, more than in other games, and especially if you were the commander or top scoring player.
Payday: The Heist - I expected much more from this game, but for some reason it doesn't really float my boat. Essentially L4D2 with robbing banks instead of shooting zombies. It doesn't seem very intuitive, especially the HUD. That's one of main reasons why I got put off, along with lack of communication. Maybe I have to give it another chance.
Team Fortress 2 - Everyone knows TF2. It has the best microtransaction system I know of and as far as I'm concerned, money gives you next to no advantage when it comes to combat. People still throw money at Valve like there's no tomorrow, though, so I guess they deserve props for achieving that. It's the game I've played the most (over 1300 hours when you count in idling and rendering videos) so naturally I'm the most comfortable with its mechanics. With 9 classes there is something to suit everyone's playing style.
Tribes: Ascend - I have very limited experience with this one, I disliked the mechanics of the game (the whole surfing and jetpacking deal) so I promptly gave up and uninstalled it.

Out of the whole bunch, it's really hard to say which one is the best. I would recommend all of them except for COD (for obvious reasons, but I'm not objective here), Payday and Tribes (probably good games, but not fitting my personal taste).