Who is your favorite Ben 10 villain beside Vilgax?

I say other than Vilgax because we all know you can't beat the protagonist's arch nemesis, like Batman with Joker. That and it would be too obvious. So besides Vilgax, who is your favorite Ben 10 villain and why?

For me, I'd have to say Khyber the Huntsman. While I liked Omniverse overall, I have to admit that the biggest reason I watched was for Khyber. Why I liked him:

-I'd say his introduction was reminiscent of Vilgax in the Original Series. In the shadows watching, intimidating, mysterious, and charismatic. You have no idea who this guy is but you know he's a serious threat.

-His motives. Khyber is different from other villains who fought Ben for the Omnitrix. Where most of them wanted the Omnitrix for power, or to sell it to the former for profit, Khyber sought out the Omnitrix to be his greatest trophy, to prove that he was"the greatest hunter in the galaxy". It's funny, I've never found myself too interested in the hunter villains, but I guess in the universe of Ben 10, I liked it as it offered something different in a villain for that series.

-The Nemetrix. Even though it was Psychobos who created the Nemetrix, you know that this device was fit to be Khyber's signature weapon. I really liked the idea of the Nemetrix, transforming it's wearer into vicious predatory alien animals that were actually the natural predators of the aliens in the Omnitrix. It was creative for what you could call the anti-thesis to the Omnitrix. Plus, it added a new bunch of alien transformations to like outside the Omnitrix (favorite predator is Tyrannopede). I wish we could've seen more of the Nemetrix and more predators for the Omnitrix aliens.

And there's other stuff like his appearance, personality (he's calm, intimidating, patient), etc.

And there you go. Khyber is my favorite villain in the Ben 10 franchise. I really hope he returns in the Ben 10 Reboot (if it turns out good)

My favorite villain would have to be Aggregor, I never cared much for Vilgax. Also according to Dwayne McDuffie:
Aggregor was a much greater threat than Vilgax, even before he became Ultimate Aggregor, he is one of the few villains that was never beaten by Ben himself. Aggregor has none of the previous villains weaknesses (except being mad with power). Instead of sending his henchmen for the most essential of tasks like the Highbreed, he prefers to do them himself. He always thinks his plans through, unlike Darkstar. He is not arrogant enough to underestimate his enemies like Vilgax. So yeah, he's a pretty awesome villain Omniverse screwed that all up among other things, he seemed to antagonize Kevin more which I also liked I could name some lesser villains that I like but maybe later.

Favorite Villian is Animo since i like his persistence and the fact that even though he always loses he keeps trying. I also like how he brings comedy to the show whenever he appears but also can bring that sense of danger whenever its needed. Also how can you not like all those mutant animals he makes.
My second favorite villian is Albedo. I have always been a sucker for doppelgangers and its even better that he actually has a reason for wanting to defeat ben other then just wanting to take down his other half like most doppelgangers in other shows. What he wants is understandable i wouldn't want to be stuck in another form other then my own. Just how he is basically a clone of ben but is a totally different person in itself is pretty awesome. Plus how could you not love the person that Created the evolutionary functions on the Ultimatrix, The Recreated Ultimatrix, and The Nemetrix.