Hunter was a very unique class like Creed said. So was druid, druid shape shifting was incredibly unique and cool. As was shaman with the totem mechanics. Paladin too with the different blessings and cooldowns and auras, it was a far more unique class than the mix of a shitty warrior + a shitty cleric that EQ offered.
Rogue was also a huge evolution from EQ, you lost some of the non combat utility because there was no corpse dragging but WoWs stealth with distract and sap etc was pretty cool.
Most of the classes in classic had truely unique playstyles in fact. The homogenization really came as they pushed the raid sizes down after TBC and really embraced the move from a medium paced game to a very fast paced game.
Being blind to the good things they did is bad, they developed some truly great classes and anyone who thinks most classes were homogenized or played remotely similar to each other in classic or TBC is retarded.