I went with The Wii, although I'll probably get a 360 in the end. Speaking for the Wii, right now they have a rather dire selection of titles, but I think that's deliberate so that their virtual console looks more appealing. With stuff like Super Smash Bros. coming out though, it's got a bright future, so while it's a bit bleak now, there are a lot of good things coming out. The Mario game, Batallion Wars 2, Metroid, etc. etc.
It really is the only problem with the system thus far. It's very fun. I think either way you go though, you won't be disappointed.