Red's Pikachu is awesome, but easy :P
However, I've got to admit, Red's battle was a sort of anti-climax for me, and Lance seemed much more epic. Possibly moreso the first time, when I was closer to his levels, and he had 3 Dragonites.
I think the hail ruins the atmosphere of Red's battle - The exclusive backdrop to the battle helps in Lance's.
In Diamond Dust, where you're just battling in snow, no hail (It always looked more like snow than hail to me, anyway), I'd imagine it's pretty special.
However, overall Lance always wins it for me. Mainly because if we were really in the pokemon world, he'd be my idol, and I'd only want dragon pokemon, to be like him.