Gotta say MMORPG, I'm a huge fan of World of Warcraft, been playing since 2004. Close second would be FPS's, Halo: Combat Evolved was the first video game i really got into, back in 2001.
Personally i don't see a humongous issue with MMORPG's, i mean, if you want to play Xbox live, you need to pay for that. To me, the whole "I don't want to pay after I've bought the games" is sort of like saying "I don't want to pay for the internet because I've bought the modem".
Having said that MMORPG's are my favourite, that's just because I like World of Warcraft so much. That's the only MMORPG I play

. Definitely play more FPS's: Halo 1+2+3, Far Cry 2, COD4 (and soon 5), Bioshock, etc...