To me, it seems that we haven't talked alot about the Marines in One Piece. I know we've seen some interesting pirate crews, but there've been some Marines that've stood out to me.
As for me, I'm a fan of the bizarre Marines we've seen:
1. Monkey D. Garp: He grasped my attention from the start. To think that there was someone so eccentric among the Marines was a big shocker for me. Even before we found out he was Luffy's grandpa, his weirdness, and the dog-head helmet made me very interested.
2. Ao Kiji: I liked how he went from lazy-guy to serious Admiral in a matter of seconds. His past encounter with Robin got to me, too.
3. Nezumi: The sneaky bastard in cahoots with pirates has a special place here. He really got managed to piss me off when he revealed that he was with Arlong for the money Nami was gathering. The whisker moustache and mouse-ear hat were neat to me, too.
4. Smoker
5. Tashigi: Her near-sighted antics got a bit old after awhile, but I still liked her dorky design.