I mainly play MiniSquadron and Inotia 2 now. I also play Tales of Symphonia, Tales of Symphonia 2: Knight of Ratatosk, and Resident Evil Umbrella Chronicles for Wii. I guess I play both platforms equally.
Interesting comment... I love my iPod Touch 3g, but the battery life with 3D gaming is weak. I can surf the net, read books, or watch a video, and a full charge lasts roughly 5 to 6 hours. However, if I play a 3D game the battery seems to drain at a rate of about 1% every minute or so - a full charge lasts less than two hours! I can only imagine it's because the processor draws a lot more juice when crunching all the numbers for 3D math..?
I don't use it as my primary gaming platform. The iDevices have pros and cons as a gaming platform. The good things are the ease of downloading the games (though it may lead to buying too much), many devs are here on TA so it's easy and direct to give feedback, and the touch controls are quite adjustable. The bad things include short battery life on many games and the touchscreen isn't as accurate as physical buttons, may miss taps (infrequently) and thumbs take a lot of space from the screen. I use my Mac/Windows more, though. I personally prefer a few large, very polished etc. games (probably getting Dragon Age soon ) rather than many entertaining, but shorter, not so deep etc. games, but each to their own.
Yes, it has become my primary platform. Portability and playing in bed can't be beat. I am also not a fan of of casual games, but I got into point-and-click adventures hardcore on the Touch - a genre which I never tried on the PC and which wouldn't have worked so well for me on a stationary platform, IMHO. Also, there are enough good turn-based strategy games and retro-style WRPGs on the appstore to otherwise entertain me. Battery life is a concern, but since most of my games are 2D, it usually lasts me more than enough for my dayly fix. I love my PC as much as ever, but I have less opportunity to play on it than on my Touch.