I had my moments where I played a lot of CoD and Battlefield, then it died off and now im really into shooters such as CSGO, Planetside 2, Destiny, Renegade X (which is a really neat game imo) and the Borderlands series.
CSGO, while it has it's toxic members (which all communities have tbh, but they are mainly visible in the bigger ones), still is a impressive game and THE competitive shooter atm. Always fun to play with friends, but solo isn't much fun when you end up with people insulting you 24/7 :P
Planetside 2 is a example how a F2P game can be without the instant P2W accuses, though I haven't played in a while, so my criticism can be outdated, but I feel the F2P gamers are at a disadvantage cause of having a slow start, not being able to make much use of air units and the fact that the ingame currency is gained rather slowly makes it a tad P2W anyways, but the massive battles you can have (it's like unlimited vs unlimited vs unlimited) are just worth it so much. Strong PC advised tho.
Destiny has been crapped on with bad story, forced to play this long cause of weekly rewards in raids, but the game is just addictive imo. I keep hunting for that one exotic weapon I will never get but I can have hopes for it. Loot system is completely RNG based and it can end up with you getting the worst things in the game while you carried the entire raid team... or you can just get the Vex Mythoclast 3 times in a row :x
Renegade X... no reason not to try unless you don't have a beefy PC. Why not? It's completely free, no microtransactions whatsoever. Plus it has a gamemode no other shooter has. While the gunplay feels really old (cause they want to make people relive the old C&C Renegade days) a lot of stuff and balance has been added to it. Plus I get to drive a two-barreled tank, thats just amazing :D
Borderlands... is just Borderlands. Loot, loot and killing creatures and bandits and more creatures. While I felt TPS was lacking in endgame (got fixed plus Clappy DLC is amazing), BL1 and 2 were the games to play. BL1 has no FPS slider on PC (rip pc gamers) and BL2 was mainly focused around slagging enemies when reaching the Ultimate Vault Hunter Mode, both have their ups and downs...