The best console is, imo, the Wii, but that’s because Nintendo have a long history of excellent and innovative controller and interface design, and a commitment to simple, fun gaming, rather than a top-end graphics processor.
The biggest strength of PC gaming is the flexibility of control – USB devices (with or without drivers) have really made it the most flexible platform. The only attendant problem is price – a decent PC is expensive. Unfortunately, in my experience, many of the companies that design games for the PC have really forgotten the basic mantra of gaming: FUN.
I play Battlefield 2 every day – not because it has the best graphics, but because it is, with the right players and server admins, brilliant fun. Compare with the Wii – I play Mariokart online regularly (although not every day) for the exact same reason. However, the nature of the game is such that it doesn’t require extensive and distributed community involvement and management to be fun; It’s just a fun game by basic design (even if I find the game’s brutal random vindictive streak to be frustrating at times).
The benefits of buying a computer just for gaming are control and community – if you get involved with the right gaming community, it can be a very, very rewarding experience.