A topic I find interesting, excuse the following essay...
For me it's all about gameplay, and next-gen gameplay doesn't neccessarily need a next-gen machine, I think. More next-gen thinking.
Gears Of War was the first game on 360 I really "wowed" at, but not purely because of the fantastic graphics. More because of the fact that I felt you were letting your team down when you died. Any game previous to that and if I died I wasn't too fussed, but when it's 3v3 and one of you is snipered, there's only two of you left and you're at a big disadvantage.
I felt like it was quite close to real-life, in particular paintballing, they'd captured the emotion superbly. So I was shocked to open the case, read the manual and find that the introduction said something along the lines of "we feel next-gen is about gameplay experiences; during the creation of the game we went paintballing a lot, and that is exactly the type of atmosphere and pressure we aimed to put into Gears Of War." I was stunned, because for them to get that atmosphere across to me so accurately was just... Scary.
But as great as it is, you could put that game on a PS2 and it would be just as good. The graphics would be worse obviously, and it would be a shame, but the game would still be just as much fun to play.
After GoW there's been a couple of games I really love; Bioshock, Call Of Duty 4, FIFA 08, Forza 2 and Mass Effect spring to mind. But of all the games I can think of only two would be impossible to put on last-gen hardware (FIFA 08 and Forza 2 because of the massive physics engines - and I mean thank God, because the graphics in Forza 2 are so bad it would have looked like a fucking dog on the original Xbox, the ratio of the console's power being shared between gameplay and graphics is fully evident).
So what do I want to see in next-gen games?
I want to see games that use that power more - for sports games I want to see the power devoted to the physics engine, which is incredible in FIFA 08 with every single thing being accounted for, from the spin of the ball to the pressure that the striker is under. For FPS games I want to see more depth - world war, pick an army and battle for it, with cities or entire countries being taken over by your army. I want people to try and invade our cities, to take them back. Something you could lose yourself in for a few months. For RPGs I want to see more things being taken into account - lines of dialogue not being repeated when you visit the same character again, much more storyline deviation being available, more than one or two possible endings.
As for which console is the best-equipped to do all of that, well power-wise it's not worth seperating them because the difference doesn't matter. I've read a million times that the 360 does some things better and the PS3 does some things better, so technically it's pointless saying one is better than the other. But as for games... There's two games I want that are currently available on PS3. I have a drawer of twenty games that I play and love now, today, on the 360.
The PS3 doesn't have any decent exclusives as far as I'm concerned, decent as in must-haves that I will be sitting here and feel I'm missing out on when they're released. Apart from Metal Gear Solid, which honestly, I think has gone a bit crap. It was great at first but now there's too many ninjas and walking-nuke-shooting robots. I'd much rather play something that's either totally realistic or totally futuristic, rather than combining realism and fantasy (which is what the Japs do best, hence why I'm now very worried about the future of PES looking at the latest release - and the Japs love PS3/hate Xbox 360).
So personally, and everyone will feel differently, I prefer the 360 and I have absolutely no intention of buying a PS3. It would be a waste of time because you buy a console to play games on, and I'd take 20 great games over 2 great games any day of the week.