I dont know if I could narrow it down to only 5, but here are some nominees:
Super Mario Bros. 1, 2, 3 (NES)
Super Mario World (SNES)
Mario 64 (N64)
Chrono Trigger (SNES)
NBA Jam Tournament Edition (SNES)
GoldenEye (N64)
Unreal Tournament (PC)
Mike Tyson's Punch-Out (NES)
Wrestlemania 2000 (N64)
...I'm sure there are many more I'm forgetting
I'd still have to say that Nintendo has had the best line of systems ever. Never owned a Sega, Owned 2 X-boxes and sold both before opening them, and only had a Playstation for a week before I sold it. Havent bought a GameCube yet tho, b/c I'm waiting on some games and it doesnt matter about the DVD playback since I have a DVD player.