I like all three brands a lot. Would probably consider myself a Nintendo and SEGA fan though. Favorite genres:
1. Arcade-style score attack (don't know if it counts as a genre, but it's a style of games I love a lot, and we don't see enough of anymore. Good examples: Galaga, Dig Dug, Asteroids, Tempest, Pac-Man, NiGHTS into Dreams, Crazy Taxi, Jet Set Radio, Tetris, Gradius, REZ)
2. Platformers, both 2D and 3D (Mario, Sonic, Rayman, Spyro, Crash, Ninja Gaiden (NES). Also Metroidvania style platformers and puzzle-platformers)
3. Action-Adventure (Kind of silly genre, since it can almost be anything, I guess some games just don't have a fitting label. Zelda, Shadow of the Colossus, Okami, God of War, Red Dead Redemption, Luigi's Mansion)
Also like a lot of third-person shooters, FPS, beat-em-ups, rail-shooters, arcade-style racers (not open world ones though), Fighting games (Although I absolutely suck at playing them),
Generally not a fan of RPGs, most of them are just too long and poorly paced, I do like a few though, usually the tactical ones.
I dislike sports simulators, like FIFA, Madden, NHL etc. I do like the more arcadey sports games though.
While I like a lot of offline-multiplayer games, I absolutely despise anything that has to do with online-multiplayer, or requires any internet connection in general. Only exception: Mario Maker.