Being an owner of all three latest consoles, I can say each one has its advantages and disadvantages. It is important to remember what each console lacks, and which other can make up for it. As of yet, the PS3 library is not all so impressive. It will get better, guaranteed. The Xbox 360 has some good games as it is, personally though, I am a little disappointed at the RPG offerings, but that is just me. Gears of War was a good game within itself, the world of co-op campaign is a good one, online co-op makes these games so much better. The Wii I would say is the leader in "fun" games. Those type of games that everyone can enjoy and does not require you to throw a whole heap of time into.
The PS3 offers the most potential in expansion, sad though that Sony hasn't been taking advantage of it they way that they should be doing. The Wii offers the most unique gameplay experience, with its control and all the possible add-ons you could make with it, the possibilities seem almost endless. The Xbox 360 has the big library possibilities, with its software very similar to Windows on the PC, it can easily bring in a bigger library. What I would like to see is game ports of older games come in. C&C3 showed it could be done somewhat effectively, use a keyboard and mouse, you could be golden. Imagine your classic games like as Warcraft 2 & 3, Starcraft, previous C&C games, or various shooter types and RPGs of the past PC years brought to life? It seems almost like an untapped market Microsoft didn't consider. This would make their "Arcade" seem like a pointless endeavor.
What all three lack? Divx/Xvid support! All three have the processing power necessary for it, but none of them offer it built-in. Xvid is all about open source, a good many would be overjoyed with this option, something as small as this could even increase sales, something the PS3 is suffering in currently.
Backward compatibility? Sony has done a so-so job, Microsoft has done a very iffy job on theirs, the fact you have to bring a list with you for either console is disappointing if you plan on visiting a Gamestop. The Wii since due to not changing much in the core of their console, has the best success, not unexpected ofcourse.
One thing I tip my hat off to Sony for is including Blu-Ray. Sure this increases the price, but if we factor in Microsoft's add-ins to equivalent it, we end up over the price and taking up more space, I didn't include the wireless adapter either. With it bundled, the PS3 can have all its games in that format, allowing better in-game movies, more complex worlds, and no need to switch discs.
Square-Enix should really have tapped into this. A Final Fantasy Collectors Edition and Dragon Quest Collectiors Edition both would sell greatly. They could alleviate compatibility issues and release a guaranteed to sell PS3 game bundling in all PS2 and previous console and handheld games into a single game disc. Sadly, this would be impossible to do with the 360 due to it being only able to use DVD9 discs. I hope by next time new consoles come out, they will at least have HD DVD/Blu-Ray combo drives. I'd expect by then, the market will shift much closer to that.