I purchased my Xbox 360 first, because, well, it was first

. It is a great system for the games I buy for it - racing games and skateboarding games. The controls for the 360 are parallel to none - if you enjoy racing at least a little, you need a 360. I even d/led the Microsoft driver to my PC and use my 360 wired controller to play older (but still fun) PC racing games. I'm actually not a huge fan of Halo or some of the more "mature" games for the 360. I just really love the fun ones (the 360 version of Project 8 is waaaay more interesting and challenging than the Xbox version).
My wife got me my Wii in May for my birthday. No lines, just had to call the store before it opened on a Friday to see if they had any shipments (they had 14, we got the first one since we got there 3-5 minutes before the store opened, the rest were gone in an hour). I love the Wii. Graphics are not everything - Nintendo has clearly figured out the way to sell consoles - get out of the uber-geek zone. We regularly have lots of people over for parties at our house and things of that nature. Before the Wii, the only video game people have widely enjoyed at our house was DDR. The Wii has the same effect. It's easy to do, it's fun, and it gets people who have no idea about the finer points of a CPU engaged in the game and laughing and having a general fun time. Some games such as Paper Mario still provide that solo player adventure that I enjoy most (my wife prefers the games where 4 people are playing). And the old nintendo games are great for nostalgia.
The PS3 holds no interest for me, and I'm a pretty big PC gamer (I tend to think that that's who Sony targeted with the PS3). First of all, the price is terrible (getting better soon, but still awful). Look at this...I purchased a Wii, 1 extra nunchuck, and 3 extra controllers for $390. The PS3, after the price drop will STILL be more expensive. That's insane. And for what? The PS3 certainly doesn't have a better racing controller, so as a 360 replacement for me, it's worthless. None of the exclusive games so far are anything special. And there's no way anyone who's not super geeky will want to touch it - making it another incredibly expensive toy just for my use. No thanks!
I've been pretty disappointed with Sony in the past, but more so lately. The driving force for me to get the PS2 was FFX and DDR. I don't think FFXIII will be enough to get me to purcahse a PS3. Of course by the time FFXIII comes out, the PS3 may be $300.
In February here in Portland, the PS3's were overflowing the shelves (even 360's were harder to find...and they've been out for a year). It's July and most stores don't even have a Wii console section as they just stack the shipments they get behind the cash register because they'll sell out that day. I think the PS3 is actually the new dreamcast so far. Both the 360 and the Wii are having incredible success.
I have owned every console made since the original NES (I realize there were others before then, but that's when I got into it) - even the 3DO :-D. I currently own a PC, N64, Gamecube (which now sits in the closet due to FULL AND COMPLETE COMPATABILITY ON THE WII - thank you Nintendo), Wii, Xbox, Xbox 360, and PS2. I will probably not own the PS3. Give me a reason, Sony.