I liked Gears 2's Horde mode on Security. Playing as Carmine like always, lugging around that giant turret like I'm the Heavy.
That laser map was the best.
King of the Hill on Day One or GTFO
Day One was like the best map ever
Gears 2 had a few good maps.
Like Pavillion, River... And there's a couple I'm picturing but I can't remember names