I enjoyed Gears of War a lot. It isn't the best game in the market, but it was fun as hell playing co-op when it first came out. Halo 2 is a huge leap compared to Halo 1. Halo 3 ups the ante in terms of graphics and gameplay compared to Halo 2. However as the series progresses, the campaign gets progressively worse. If you really enjoyed the campaign in Halo 1 prepare to be disappointed as you play Halo 2 and 3. If you enjoyed the multiplayer, then you'll really like Halo 3's multiplayer custom options and gametypes.