It seems like one of the mission statements of the show was to have "likeable" villains, or somehow "funny" villains. Even though I hated Caleb, I enjoyed watching him. Okay okay, part of that just happens to relate to the awesomeness of Nathan Fillion, but that's a given.
The Turok Han were big and nasty, somewhat cool looking things, but they had no personality. They were just... evil. In a way that was refreshing, since most villains on the show were layered at least a tad, but it didn't make with the humor at all.
Caleb all the way. I just wish his hair would have been shorter; the length and slight poofiness gave him a childish look which didn't fit with his personality.