My favorite is the typical 26 episode. The big, gaping series such as Naruto and Full Metal leave me with too much frustration. Stuff like Cowboy Bebop and Trigun pissed me off, sure; but I also felt that it had excellent character development as well. Not that FMA and Naruto don't, it's just taken so long to do so, and one facet of backstory can come out at the worst time (i.e. backstory on Rock Lee in the middle of his fight with Gaara. Sure, it was rad, but their fight was far better).