Way too many to really name a favorite. For me, this is equivalent to asking me who's your favorite parent. It's one I can't answer because I like all of the following equally. But just for different reasons for the most part. Anyway, here is just some.....a small portion of my favorites in no particular order:

Batman - TAS

Spiderman - TAS

Wolverine, Morph, original Sentinels - X-Men TAS

Oliver Queen - Arrow

Emily Thorn, Aiden, Nolan, Jack - Revenge

More later.

It's mostly cartoon characters for me.

Billy and Mandy
Ed, Edd, n Eddy
Basically all the Looney Tunes characters
Scooby-Doo the whole gang
All 5 Teen Titans
T-bone and Razor (SWAT Kats)

Non-cartoon Characters

Buffy the Vampire Slayer
Rick, Daryl, and Dale and the woman with the samurai sword from The Walking Dead
The 4 main people from It's Always Sunny In Philadelphia