I think it's the Mankind one. It was Cole's best by far. All of it. From DX/Corporation brawl, Austin coming out, the 3 count, after match. I'm not going to give it a lot of thought, but I doubt I'll find a better call he's made.
"he's come a long way since sleeping on the floors of motel 6's, from sleeping in his ford thermon learning how to wrestle. he's been known as dude love! cactus jack! mankind! but tonight and forever, Mick Goley will be known as WWF Champion!"
Whenever he first said "vintage Undertaker" that is his only real epic call and it's one that will last forever, when they do video packages of Undertaker in years to come, that will be the voice over they use.
In all seriousness, his commentary was very good for Eddie and Mankind's title wins, as others have said. I actually never thought he was quite as bad as others have said, even when he was racking up Worst Announcer Awards from the Observer.