Well, it should be an action series, but have a good plot and characters. I tend to dislike the really outlandish/superdeformed types of comedy in a action series (comedic-action shows like One Piece don't appeal to me, and Full Metal Alchemist's constant comedy with Armstrong, Ed, and Mustang ruined all the 'serious' moments for me) and prefer comedy to be more verbal or light slapstick. Fanservice is also a big turnoff. Fantasy is definately my favorite genre (but anything that allows for a variety of unique powers and characters will do). It should have little to no filler episodes, and an actual good ending (none of those extremely open-ended-not-much-resolution type of endings, or those weird 'what just happened?' types of endings) Examples of recent shows I enjoyed are W.I.T.C.H. (my favorite series, the best example of what I look for in a show), the early seasons of Teenage Mutant Ninja Turtles 2003, Mega Man Star Force (Tribe left a lot to be desired, though), and Beast Wars and Digimon Adventures.
The opening to Soul Eater looks interesting enough, though. Is it licensed?