Okee -you refer to the battle of the Hornburg. You may hear people call it "The Battle of Helm's Deep," but it was known in the books as the battle of the Hornburg.
At that battle, Legolas and Gimli make a game out of who kills the most orcs.
Gimli wins 42-41.
Aragorn was one of my favorite characters, as was Legolas and -of course- Gandalf. But my two favorites were Boromir and Samwise.
Boromir may have given in to the Ring, but he redeemed himself in the end and died in valor -as a hero.
Sam was the most self-scrificing character I've ever read in any story. Especially in the confrontation at Cirith Ungol. I won't say any more, because that's coming up in the next movie (even though it should have been in The Two Towers)!
In truth, it's really hard to pick a favorite character, because all of Tolkien's characters have so much depth and realism that it's hard not to like them all.
Especially the Ents!
Hoom-hom-musn't be hasty!
The Elf Fingolfin and Morgoth, Sauron's Master. . . from The Silmarillion