I would go 6 PS or higher, 5 is kinda weak unless you're using a pierce or blunt weapon.
Then again I don't mind being kinda on the slow side so it's definitely got a lot to do with preference & play style.
21/18
18/21
18/18 (extra skill points for something else)
21/15 (same as above)
24/15 (slower more tank build, still effective but you probably won't be winning any foot races.)
15/24 (use a blunt weapon or pierce, and with 8 athletics the shorter range & slower speed of the weapon will be less noticeable and easier to deal with, blunt with knockdown is especially dirty with a build like this. PS: you will win foot races but you drop pretty easy after a few hits.. IF they can hit you.)
The more STR and health you have the more staying and stopping power, the more AGI, the easier it is to pick and choose your fights. Faster players aren't usually forced into engaging except by their own terms.
I agree with Xant on weapons and armors, you don't want to be too weighed down by armor, especially if you're using a lower athletics build & the Danish/German can cover a wide variety of niches on the battle field. For a lower strength build, like 15 str or 18 str it's nice to have a blunt weapon to deal with tanks but the great sword's stabs work well too so it isn't 100% necessary.
Good luck hope my wall of text was slightly helpful.
