Halo 3 is better if you want multiplayer action... Bungie is always adding maps and variants, they even added 500 more achievement points, and Bungie.net tracks all of your gameplay for you to view after linking your gamertag. Gears is better in the sense of campaign and gameplay controls, the game flows more like a movie. The graphics are alright in Halo 3, there are many patchy spots where they focused more on everything else. Gears of War 2 has rediculous graphics, and I would choose that over Halo 3. Although I recomend getting both. They both have great storys and are very fun to play. I'm sure you can find Halo 2 used somewhere.