Captain Jean Luc Picard for Acting, James T. Kirk for being a sort-of-Commander Shepard (like Chris Pine better than Shatner though, the original Kirk was overshadowed by Spock, McCoy and Scotty), and Janeway for being the best acted female character that leads her own series.
..But Picard still wins in the end, for me. TNG is the series I grew up on, and Captain Picard always seemed to embody the more core values and messages (diplomacy, philosophy, literature, submarine-esque warfare, etc) of Star Trek overall.
Oh, and just to put it in here, DS9 was the best series for showing off massive system scale conflict and in-general ship combat (the Dominion War).