Alucard HANDS DOWN.

Archer - Fate/Stay Night
Its hard to talk about him without spoiling so much. Just go play the Unlimited Blade Works route to find out how much of much of a badass he is. Makes you wish Shiro would think like him (Well he does in Heaven's Feel but anyway...)

Lancer - Fate/Stay Night
Lancer is Archer's rival so in a way he's an anti-hero too. He's probably one of the most respectable characters in the series too. Its too bad he has such a minor role in all 3 routes though (In Fate/Hollow Ataraxia that's another story)

Vita and Signum - Magical Lyrical Nanoha A's
Powerful allmighty loli and a typical badass female swordsman. They're both awesome and they're both very respectable. Plus isn't Vita just the cutest thing ever? ^_^

Fate - Magical Lyrical Nanoha
Fate was the main reason I watched Nanoha. She's got the best design, best personality, coolest abilities and is very moe. I don't like Fate's adult form though. Loli Fate is much much better.

Suigintou - Rozen Maiden
One of my favorite villains actually. Her design is excellent and her personality is very interesting.

Vita, Signum, Fate, Suigintou,............ awesome ^_^

I say alucard or the guy from Berserk

Levi from Black Lagoon or Mugen from Samurai Champloo. Alucard is good too.

Ya, Levi is pure kick-donkey