My main platform for modern games would undoubtedly be PC.
In the second question, I also still side with the PC.

It's nothing against the other two as consoles, it's just that the games run better, control better (as I can use any control method I want), and have more options on the PC. Back in "the day" consoles had the exclusives to win my heart, but these days the majority (although not everything - and I'd say the Wii has more exclusives than the other two) of "big" games are multiplatform and unless there's no PC port or it's ported terrible there's no reason to get a console version of a game over a PC version if your PC runs it.
I own NES, Master System, Genesis/CD/32x, SNES, 3DO, PS1, Saturn, N64, Dreamcast, PS2, Xbox, Gamecube, Xbox 360, PS3, Wii, DS, PSP, Gameboy Advanced, Gameboy Color, Gameboy, Game Gear, Nomad, and a gaming PC.