Mod your xbox, get both free.
If you absolutely have to BUY one though, make it Black Ops. Halo hasn't changed since Halo 2 and reach got boring REALLY quick. Black Ops is just as addictive as the other CoDs, plus it plays way different than MW2 and it's not a tube/nade fest anymore. You actually have to have skill to win now.
Last edited by TraMaI; 11-13-2010 at 02:53 PM.