It's strange because it ought to be the other way, but I haven't yet seen an animated superhero series that really satisfied me. Whereas a few live-action movies (the first Superman and Batman, and of course Avengers) have struck me as enormously satisfying and successful (give or take Superman I's lousy ending and the bad idea to kill off the Joker at the end of Batman I). It may be that people put in more effort in live-action just because it's more difficult.