Most anticipated? Gamespot/Gamefaqs, the biggest gaming community on the net, issued a poll. Which are you looking forward to more? GTA:IV or Halo 3? GTA:IV won by landslide.
Grand Theft Auto 4 is the most anticipated. Why? Well. halo is just another FPS. Its *edited* good, sure, but its still an FPS. A genre which has been done hundreds of times before.
Where as the unique genre that Rockstar games created and pioneered with the GTA Series. Well, its unique, duh.