It's hard to just choose one. My top three video game franchises are made up of Halo, Resident Evil, and The Legend of Zelda which are all very different games. I can enjoy a good first person shooter, but I don't think I'd say it's my favorite genre. Which is ironic, considering Halo is one of my favorite games of all time. I guess it just does so many other things so well (not that FPS games are boring or anything, it's good fun). I also really love survival horror, but I also really enjoy action games. Survival horror games give me a good thrill and make me feel really accomplishing since you have to play smart in order to survive. It's about using your head and deciding how you're going to approach certain situations. But action games give me another kind of thrill, the kind that you can't ever get tired of. This is especially true for me, because I find myself playing RE5 more than any other Resident Evil game, even though it's my least favorite RE title. I guess the action genre provides me with maximum fun. But I also do enjoy me my adventure games. They're a bit more lengthier and can sometimes suffer from repetitiveness, but do give me another kind of joy I just can't quite explain. I also do enjoy me some platforming fun. They're just so addictive and weirdly fulfilling.
Now that I've gathered all my thoughts together, I guess you can say, I don't really have a favorite genre. I enjoy different kinds of video games and you can't judge them all based on genre. It's about how well the game executes its genre.