If you really want to game the system, PS is king. My 30/9 polearm build is WAY more effective than my 21/18 build; but I have more fun with the 21/18.
High damage cut weapons REALLY benefit from stacked strength. Even with the armor changes you can 1 and 2 hit people all day long. The slow movement speed just bored the shit out of me.
Currently I'm using this build with a German Poleaxe:
STR: 21
AGI: 18
HP: 70
IF: 7
PS: 7
ATH: 6
WM: 3
WPF: 130
Going for overheads or thrusts I can still kill people rather quickly unless they are in heirloomed plate. I can also take a ton of hits and not get outspammed. I'm also fast enough to run with any of my clanmates which really helps with getting the overheads in.
So if you want to be super-effective, go for stacked strength, but don't complain when it takes you all day to run across the map.