If I want to combinate group/solo without respec skill and need to chose between these 3 I would probably go for Armsman.
If we put all equal (skill, stuff, rr etc which is impossible anyway) still these 3 are close in 1vs1, maybe advantage to the hero with moose up.
The fight not gonna be as quick as 1 slam will be enough. Both will be able to land at least 1 slam (unless really badluck).
Mainly in real rvr (at rr, stuff =) it's your capacity to switch quick between your shield and 2h/polearm and using the approriates skills.
The quality of your swing will be the key, combinate with some straf /or counter straf.
On paper, something like
that. You have also a part of luck in close duel.
These 3 are good, just pick up one and master it and you will beat the 2 others.