Hmm I think Wolvie vs. Deathstrike is probably the best, but my favorite would have to be the forest scene in X3. Wouldn't that in a way count as a '1 on 1' fight? The mutant with the pine cones (
) coming out of his wrists vs. Wolverine. They were the center of the whole sequence with Wolvie taking out random mutants in between. I thought it was awesome. I remember how cool the little smirk that mutant gave when he hit Logan the first time and threw two more near him on the ground, and then he slowly brought out two more in his arms. Awesome.
I'd probably vote for that one if it was in there, but the Deathstrike is definitely one of the best.