Ultimately my vote went to Legolas an Gimli, due their combined overwhelming years of combat experience. Yes, Aragorn in a 1-on-1 against any of them stands a good chance of winning (barring, of course, a solo charge against any character wielding a bow and arrow, obviously) but here I'd say that Boromir works against his odds: he's only got a decade or two of fighting time logged, whereas Legolas has been around for thousands of years and Gimli a hundred or more.