Oh I'm not going to even choose. I have found many titles on both Wii and 360 this generation that I absolutely adore. Or if you don't believe me, just go look at my game collection which should be up to date haha. And for me it obviously has nothing to do with graphics, simply because I only got an HDTV November of last year. And I must say, it didn't change the experience at all from playing the games on a normal SDTV. Although it was crisper. So I can't even choose because I wouldn't really be saying something I think is true.
However, there are a few things I can say definitely about this generation imo. First and foremost, of the Wii and 360, the Wii has a hell of a lot more diverse and unique games. A lot of the "quality" and purchased 360 games I own can really fit into a few categories with most being considered action titles. Although the cinematic action genre really has taken over the mainstream this gen and become the big budget games that usually "reviewers and gamers enjoy" it really has left a lot of the diversity to the download section. I really don't download too many titles (only one on 360 which was Castle Crashers which I thought was atrociously boring). But on Wii I have bought and enjoyed many of its premiered titles that have ranged from gory beatem-ups to point and click adventures. And I've really enjoyed being able to have that "freshness" from a lot of those titles as I play into that diversity. I'm not going to say diversity doesn't exist on the 360, but from what I've bought I've felt like it has given me more diverse and fresh experiences.
Now what I thought would have been a better question, is what developer/publisher have found the better games on. And like so many generations before it, that has easily been supplied by none other than Nintendo themselves. Although some discredit them a little bit this generation, to me their quality and high standards of production has shown this generation again and have delivered some of the, if not the best, experiences out of all the other developers I've bought games from. So if that would have been the question, then Nintendo would have been my answer. But for the sake of the thread... both, or in my case Wii and 360 because I don't often play my PS3.