I rank them like this:
Xbox 360.
Playstation 3.
Nintendo Wii.
Why?
Well it breaks down like such;
The Xbox 360 is my first choice simply because of the games, it is my favourite console for the gaming experience it offers. It has (arguably) the best selection of retail games today. The online experience is fantastic, of course, it's not free unlike the Playstation 3 or Nintendo Wii but I'll leave you with this quote
"You get what you pay for"
Its' online experience is the best out of the three consoles, you have to pay for it, but it guarantee's that you get a decent service (and we are talking about Microsoft).
It isn't perfect (biggest recoil history, the infamous Red Ring of Death; RROD, service is a little off)
As for the Playstation 3. I wanted it mainly for the Blu-Ray / HD DVD. It's likely the cheapest Blu-Ray player on the market (atleast here it is). The interface is a little annoying, but it's fine if you've ever used a PSP. However the game library at the moment is small compared to my 360 collection. It's online experience is weak compared to the 360 and Nintendo Wii. Infamous, MGS4 and Little Big Planet seem to be the only best-selling titles it's ever had. However, I do watch much more passive media, so therefore my Playstation 3 has likely been turned on much more than my 360 or Wii.
Finally, the Wii. It's still wining in sales compared to both the 360 and Wii. It has a huge gaming library (historically speaking that is). The whole system forces game-makers to think a little about their games and how they make them. Unfortunately this is it's downfall. Like the Playstation 3, the game library (again) has very little that make me go out and buy games for it. Nintendo doesn't really care about the hardcore gamer anymore. It is targeting a whole new family.
Things such as the Wii Fit pull in other customers (other family members' also) which is one of the main reasons why it's still wining in sales.
Unfortunately that doesn't suit people, such as myself who just want to play games and have fun.
Now if the PC were classed a console, it'd be first for sure. But that's for another thread.