I always enjoy going back and watching old Siskel & Ebert reviews just to watch them spar. Those two guys just had such fantastic chemistry and a pathological need to get each other's goats. This is one of my favorite running threads.
First up is their split decision on Cop and a Half. Gene hates it; inexplicably Roger likes it.
This is referenced again in their review for Broken Arrow, where Roger actually gets Gene to change his vote from thumbs up to thumbs down.