Like monocle said, Xenoblade on New 3DS. It wasn't a pretty game, but neither was the Wii version, and it ran perfectly well.
Virtua Fighter on Sega 32X is actually better than the Saturn version of the game, with simpler character models but none of the flickering or instability of the Saturn version.
Doom on the SNES and GBA. In the former case, Doom on SNES was somehow playable despite the SNES's wimpy hardware compared to the 5th gen consoles getting ports at the time, and even did a better job at recreating some of the original level layouts than most ports. The GBA version gets credit for coming early in the system's life and being arguably the first solid handheld FPS.
Prince of Persia had a fairly good NES port.
Love and tolerate.