If you don't care how long the fight lasts, the best build in the game is pretty obvious.

1 handed + shield
rank 5 shield
rank 5 bodybuilding
rank 5 willpower
rank 5 man-at-arms
leech
weather the storm
picture of health
comeback kid

You won't even come close to losing. No matter what the fight is, you're only several dozen turns away from victory.