I prefer manga. But I've seen some anime. I'll list the ones I've finished.

[hider=Listy]
Pandora Hearts
Paradise Kiss
FMA (The first one before they screwed everything over...)
Bakugon of all things.
I've seen all I can see of HunterXHunter
Ouran High School Host Club
[/hider]

I literally can't make a list of all the manga I've finished, but I list my favorites that I'll read over and over again along with about how many times I've read it.

[hider=Listy]
The Breaker & The Breaker:New Waves (Incomplete Manga. I've reread it like.. 3 times.)
Saver (Like 7)
Tokyo Crazy Paradise (I have this one downloaded on my phone so I can read it even without internet. -cough-)
Samurai Deeper Kyo (In the process of rereading this one. It's long... I've read it like 4 times.)
Hot Blooded Woman (Like... 7 times.)
Basara (vfnvfdvdf. Good read. I've read it like 3 times. It's another long one.)
Red River (Like... 7.)
Immortal Rain (Twice... I need to read it again.)
Beauty Pop (2 or 3?)
[/hider]

I'm sure there's more I'm forgetting but yeah.