Pokemon Gen 2 for me personally. Honestly, until I recently where I replaced the battery and replayed the first 3 gens it was my favorite, but now I'm more shifted to preferring Gen 1. I'd still give it a near perfect score because it's a classic. That being said, had I been a little older I could see Quake 3 taking that spot for me. I have great respect for the Quake games, especially since some of my older friends during the Halo 2/3 era were quite fond of it.