My Captain, Mal
This picture is one of my favorites for it captures three big influences on my life. I've written elsewhere here as to how Shatner is my surrogate father. Stewart's got a great command of stage and screen--heck, even his voice overs are powerful.
But Nathan Fillion--that man IS the captain of choice. Mal Reynolds. Part pirate, part captain, underneath it all a Sargent and sailor and in spite of himself, a swell guy. Throughout the series, Firefly, he says variously that he's a bad guy, a rascal, a mean old man, destined to a special hell...but in my books, he's the imperfect hero we all want to be.
If the scene above were real, not photoshopped or a joke in a wax museum, I am certain both of the Star Trek captains could take direction from Mal. I know I do.