For the record, I've played every Halo to date and I fully intend to play Halo 4 . I expect it to be fantastic.
I have also played and enjoyed every Gears of War , and I have 15 other Xbox 360 games in my collection as well. I've got maybe 70 PS3 titles but that's because- 1. I work for a PlayStation-centric website and I get a lot of PS3 review copies, some of which I keep, and 2. There are simply waaaaaay more worthwhile exclusive titles on the PS3. And for the latter reason, the 360 mostly just gathers dust these days.
However, there is one game I'll go back to and play. There's one game that will force me to keep my Xbox 360 and amazingly enough, it's because this title allows me to relive the glory days of the PS1, when the JRPG ruled. The game, of course, is Lost Odyssey , which featured a true turn-based mechanic ('gasp'), a pretty decent story, strong characters, beautifully drawn environments, and perhaps strangely, some of the finest writing of the generation. I'm not talking about the actual script; I'm talking about the wonderfully penned dream sequences that were essentially short stories. A professional did those, I'm fairly certain.
At any rate, I definitely want to go back and play it again, and I can't say that about any other 360 game. Hell, I'm willing to keep the 360 plugged in and ready to go until I have time to play Lost Odyssey again. If you were a hardcore JRPG fan in the PS1 days like me and you haven't played the game in question, buy a 360. No, I'm not kidding. You can thank me later.