I have lots. Some fairly recent favs of mine are the Superman-Parasite fight from Superman #156-157. I was always a fan of the Parasite, and he seemed more menacing in that fight than he has been portrayed in recent years, so that was really good to see.
Another fave of mine is the Superman-General fight from JLA #36-41. The World War Three arc. The General's got guns blazing, bullets bouncing off Superman, Superman cuts off his arm with his heat vision, ...it was just an awesome fight.
