I'm just going to be bold about my system preferences coming up this Christmas, in case any of you are wondering. I'll give the goods and bads of each.
1) XBox360
Goods: It's out already, so there's a huge selection of games. Xbox live arcade has an excellent selection of small games, and will be the hosting platform for Castle Crashers. The graphics are amazing, and several great titles, including Gears of War and Halo 3, will be releasing on this system. The interface is awesome, being able to communicate to your windows Media Center PC, allowing you to stream all your music from your harddrive while you play your favorite games. Xbox 360's multiplayer is phenomenal.
Bads: Expensive. Everything's expensive, including the games. You'll be paying $400 for the Premium pack, and its probably not the greatest idea to get a Core set.
2) Wii
Goods: Fantastic new multiplayer, awesome control style. Brilliantly designed controller, cute package. Back compatible with Gamecube, even down to memory slots. Cheap, sitting around $250. Comes with a game already as well. Several family friendly titles. Nintendo has a long history of well built machines, so it should stand up, even though its a brand new system. Great style, great system, great price.
Bads: Good luck finding one. And good luck finding games. There will be a limited amount of games out when this bad boy releases. Controllers (wii-mote + nunchuck) sets are going to be $60 together, so controllers are an arm and a leg to buy. Graphics are not a huge step up from Gamecube.
3) Playstation 3
Goods: Extreme graphics, blue ray player. Classic titles relaunching in new sequels. Did I mention a Blue Ray Player? You won't find a blue ray player otherwise, because Sony is running short on blue diodes. New multiplayer functionality similar to xbox Live.
Bads: Everything. The base system is $600+, minus any sort of games or controllers. The game line up is partially what you can find already released on Xbox360. The system banks on a chip that is 1 in 10 success rate of working in development stage (insure your system to death if you reserved one). The game release is slow and long. The system release is even slower, so why should any developers want to develop for a system that can't produce games? Game titles limited and will be for about a year. No Europe release, only North America and Japan, for now at least.
So you want an opinion from me? Go with xbox360 if you need a console now, because it works, its wonderful, and everyone who owns one (that I have seen) is happy with it. For the long haul, further down the road, definitely invest in a wii. At $250, you can't go wrong, and it's a ton of fun (E3 was a blast ;).
Or, go with my choice 4!
4) Nintendo Entertainment System
Goods: Features the top number of great games out of any console. Ever. Play all your favorite games, and play them at full 8 bit color. Games average about $6 right now on Ebay. The system only costs $20-30. The perepherals out with the system, such as the light gun and power mat make an excellent combo for a different style of gaming. Over 1,000 US titles. You really can't go wrong.
Bads: You have to blow into and clean cartridges to make them work, unless you get a top loader NES, which eliminates this problem for the most part. Otherwise, there's nothing to complain about... its retro gaming at its best.