As far as what I've seen the most individual episodes of, probably Yu-Gi-Oh! 5D's. But what, time-wise, I've actually watched the most, I'm not sure. Actually, it might be Yu-Gi-Oh! GX, thinking back...
Gundam - random episodes at times, entire series at others =3
Cosplays for 2012-2013
[100%] - Lucia, Fire Emblem
[100%] - Ecilan Ice/Ice Knight, Legend of the Sun Knight
[50%] - Glaceon gijinka, Pokemon Gen IV
And Potentially: Creus Sun/Sun Knight, Skarmory gijinka
Anime Revolution 2012 - Tsukino-con 2013 - Sakuracon 2013
Pokemon cosplay meet-up? =D
Shugo Chara! Those theme songs are burned into my mind!
Pokemon, just due to the sheer amount of episodes.
The Slayers, Inuyasha
Either Ouran High School Host Club or Angel Beats! With The Melancholy of Haruhi Suzumiya coming in second.