You're entitled to your opinion, but personally I'd say Duncan is a lot more respect-worthy.
For one thing he's more noble/honourable. Not that Connor isn't, but Duncan seems more so. Plus he's more friendly and approachable.
Here is Duncan vs. Jacob Kell's posse. At first they cheat by attacking in a group, but even outnumbered Duncan holds his own. He then fights Jin Ke 1-on-1, demonstrating his hand-to-hand skills in the process.
Here is Duncan's first fight with the Guardian, who possesses superhuman strength and speed. Note how he is able to parry a few blows when the Guardian uses his Flash-like super-speed.
Anyway, here Duncan and some comrades take on a group of cannibals. Note how Duncan is not hindered at all by lacking his sword (the Guardian destroyed it), as he just wields a pipe using his bojutsu skills. He also throws the pipe through a truck's windshield.