I take the 6wm because I like to rock my lordly plate so the extra wpf helps stay fast and tough.
+3 italian, +3 iberian, +3 knightly heater shield, +3 churburg, and +3 plate mittens, and a +1 hornskull bascinet
Like everyone here is pointing out, try a build you like, then tweak it the next gen.
Ive done the 21-15, my last gen was 24-15 with 8ps, and it was good but I still miss the smidgen of speed that keeps me alive more then the extra hp and damage does.