Well, I maybe don't have ten, but let's try:
1) the Pokemon's on GB, GBA and DS (from red/blue to pearl/diamond)
2) Kessen 3 on PS2, the most fine game I've played!
3) Yu-gi-Oh different games on DS, cool to play against other players anywhere by Wi-Fi
4) Resident Evil 4 (GC)
5) Monster Hunter (PSP)
6) Street of Rage (MD/Genesis)
7) Street Fighter 2 (SNES) on original version, without turbo or "
8) Legend of Zelda - Ocarina of Time (N64 - GC): not playing it anymore, but spent a lot of time on it!
And a special mention for Ôkami (PS2), too...