The Playstation 3 is a good console and will continue to have a good shelf-life, (if it keeps on getting cheaper, and keeps hauling in the exclusives).
The online features are a little haphazard, but in general its a good choice.
The PS3 can play blue-ray discs, the 360 can't. If you are interested in blue-ray and large disc space, then the PS3 gets brownie points.
For that reason the PS3 will not be my platform of choice this year, (I already have one, and a 360, but I'm not going to buy games for the PS3 this year, (except maybe one or two exclusives)).
I am getting the most out of my 360 while its still around. Its the exact reason I have an xbox (the old one) in my university room and not a PS2.
The PS2 is very popular, even today, and the ol' xbox has faded quite a lot from public face.
Now, the best games on the PS2 can still fetch very high prices pre-owned still, but the advantage of having the xbox, is that the games are generally very cheap, (barring the rare games, and the cult classics (e.g. the bioware trio)).
I got A nice sizable xbox collection spanning over 40-50 games, for the exchange of about 3-5 ps3/360 games.
Even though I am no graphics whore, alot of the xbox games still look good by todays standards, (especially Team Ninja games and Panzer Dragoon Orta). (Some companies need to realise its not always about the hardware. Good design and use stylistic techniques can make a game stand out so much more! (Look at how nice Super Street Fighter 2 Turbo HD Remix looks))
In a couple of years time, there may be an xbox successor. The PS3 may still be going stong, so the 360 games might get quite cheap, and that is when I strike! (XD)