If I had only watched the movies, I would say Obi-Wan.
After watching pretty much all SW content; it's definitely Maul & Ahsoka. The series added so much depth to Maul.
Episode one maul was pretty lame. I’m pretty sure that this sentence contains more words than all of what Darth Maul said in the first movie. I haven’t seen the clone wars in a very long time, but if I recall correctly, he’s insanely cool in that show.