Right now I can say why I'm looking forward to a 360 (right in time for the Christmas price drop) and eventually a Wii. Both MS and Nintendo seem to have a point, or a reason for doing what they're doing, whereas the PS3 seems very much like a case of 'I'll have what they're having'.
The Wii is clearly trying to try something completely new in terms of controllers. I mean, the thing is weird. New gameplay, new options, new styles. All good.
The 360 seems predicated on networking. Live is the best thing MS has going for that thing. They're getting a new influx of tiny designers coming up with weird and different things, possibly entering the market under the threshold of price. I blanch at coughing up $50 for a game, but hey, $5 isn't too bad. It's a heck of a lot easier to rationalize, that's for sure.
Sony doesn't seem to have a reason, other than Blue Ray, and that's not compelling to me. I admit I may not be their target audience, so hey. The controller seems like a pale imitation of the Wii and their networking setup isn't Live, not yet and perhaps not ever.
I know if I get a Wii, I'll have new game play. I know if I get a 360 I'll get new networking options on my console. I know if I get a 360, I'll have to buy a whole bunch of movies over again. Eh.