Oh geez. I have to narrow this down to 20? Mkay...i'll try my best. Let's see here...
1.) Renji Abarai (Bleach) - Duh. That one should have been obvious 
2.) November 11 (DTB) - He's hot, British, and voiced by Troy Baker in the English dub
3.) Shizuo Heiwajima (DRRR!!) - How can you not love a man who can punch someone straight out of their clothes?
4.) Hei (DTB) - Look at him. That's all i have to say
5.) Maes Hughes (FMA) - I instantly fell in love with this man. He's hilarious, good looking, and will literally give up his life for his friends and family
6.) Hagi (Blood+) - Mmmm...Hagi 
7.) Stein (Soul Eater) - He may be crazy, but he kicks butt and looks sexy doing it
8.) Kensei (Bleach) - He's a badass
9.) Izaya Orihara (DRRR!!) - I can't help but adore that sociopathic troll
10.) Roy Mustang (FMA) - I just adore his character 
11.) Free (Soul Eater) - He's such an adorable goofball. Gotta love him!
12.) Hisagi (Bleach) - I don't care if the man has a 69 tattoo on his face or not. He is gorgeous!
13.) Greed (FMA) - The original Greed. He was pure awesome
14.) Kyohei "Dotachin" Kadota (DRRR!!) - Love his calm, cool demeanor. Plus he's voiced by Steve Blum, so he's automatically awesome
15.) Spike Spiegel (Cowboy Bebop) - You don't wanna be on his bad side. Though...by looking at that man, not so sure he has one
Also voiced by Steve Blum...
16.) Solomon Goldsmith (Blood+) - Simply because he's good looking
17.) Grimmjow (Bleach) - He killed Luppi. Is there any better reason to like him? Oh...and he's hot 
18.) Havoc (FMA) - He's adorkable 
19.) Spirit (Soul Eater) - He may be a womanizer, but he's still an awesome dad, even if Maka doesn't see it
20.) Gin Ichimaru (Bleach) - His constant smiling and closed eyes may creep other people out, but i love it 
Whew! Man...you do not realize how hard that was for me to do. I'm sure there are, like, a billion guys i left out. But this is what i was able to come up with off the top of my head.
"Don't be ridiculous. You must have me mistaken for someone else. I didn't come here so we could paint each others' toe nails like it was some kind of slumber party. I came here to kick your ass." -Renji
Loly: "How did you get in here anyway?"
Grimmjow: "What do you mean how? Through the wall of course!"