Actual gamerscore, Halo 3 with 1670. % completed, Mass Effect 2 with 100% including DLC. I ****ing love that game.
Halo 3 - 1750 Borderlands - 1170 Halo 3: ODST 990 (Only missing Windward's firefight achievement >.<) Edit: Correction, 1000 GS in ODST now. Just got my last achievement ^-^
Halo 3, 1715 GS. I'm missing Reclaimer and Save This Film. Second is Borderlands, with 1135 GS. Third is... wait for it... LEGO Indiana Jones. My little sister loves that game, so she got 1000 GS in it. Fourth is MW2, with 910 (only missing Star 69). Fifth is ODST, with 890.