Is Stranglehold fun? I hear that it is very action movie-esque. That's exactly what I'm going for. I like over-the-top shooters (Crackdown being my favorite 360 game and the Wet demo was fun). The singleplayer campaign of Halo 3 and Gears 2 didn't appeal to me much.
Also whats the verdict on Kingdom Under Fire: Circle of Doom? I'd like to try a good hack n slash. I tried the Ninety-Nine Nights demo yesterday and thought it was meh. If Strangehold and Kingdom Under Fire: Circle of Doom have demos, I'll check them out tonight.
From that list, I strongly recommend Crackdown (the demo is on live so you can try it to see if you like it) and I recommend Blue Dragon if you like jrpgs and don't mind that you are basically controlling a bunch of 12 year old kids. Blue Dragon has a good class system.
I also have PGR4 (it was bundled with 12 months live gold, a chatpad and an extra headset) and it's pretty fun. I suck at racing games though. :( Pretty sad finding myself finishing last place in championships in the Pro stages of career on easy difficulty. lol.