I really don't think I can honestly cast a vote in this, and may sit this one out.
I own all three systems, and all of them have their strengths. The Wii is certainly my favorite, but you all know that's because I'm a huge Nintendo fan, so it naturally had the games that I liked best. I also personally liked the motion controls, at least in the cases where they were utilized well. Heck, even Metroid: Other M did some cool things with motion controls. The downsides were obvious though, since the system just wasn't powerful enough to output visuals anywhere near on par with its competition, or carry multiplats that didn't feel like watered down ports with forced motion gimmicks.
PS3 is the second for me, though I didn't pick it up until about a year ago. The OS feels overall smooth, unintrusive, and simple to me (I know that last one in particular is very subjective, but I much prefer a UI simple in both feel and literal use, as I find it easier to navigate). The PS3 also has my favorite 7th-gen controller (I really don't understand why people hate the dpad... I think it has the best one of the three!), with the only downside being the triggers, to a degree. I also am coming to love Sony's exclusive offerings, and PS+ is quite possibly the best money-saving gaming investment ever, aside from Steam, of course. The only real downside I see here is game performance, especially in earlier games, which brings us to...
360 is the third for me, but don't get me wrong; I don't think it's a terrible system. Thing is, if it weren't for the fact that multiplats often run better on 360 than PS3 (especially in earlier games), as well as the fact that I like Halo and Gears of War, I would see no compelling reason to own one. It has almost no exclusives, online multiplayer is paid (along with many other services that are free on just about every other platform, like Netflix and YouTube), and even with a paid subscription, the dashboard feels like it's at least 60% ads that waste so much space. Not to mention that Microsoft didn't seem to learn it's lesson from the original Xbox regarding the dpad: The 360 controller easily has one of the worst, most unreliable dpads I've ever seen in a major, first party controller. There were also the infamous RRoD issues, but I personally never had to deal with that.
You know what, scratch what I said in the beginning: After writing everything out, I know that 360 gets my vote. Just keep in mind I don't think it's an awful system: I just don't think it's as good as the two alternatives.