Well, if it's ANY build at all as long as they are 30/9 or 9/30, then I say that the 9/30 will win. Basically because of ranged.
Like this HA/HC here on a heavy horse:
Level 30 (4 420 577 xp)
Strength: 9
Agility: 30
Skills to attributes: 8
Riding: 5
Horse Archery: 5
Power Draw: 3
Weapon Master: 10
Archery/xbow: 189
Would beat anything except a Hoplite (hoplite is the best HA/HC counter
Or this trololol light xbow user on foot.
Level 30 (4 420 577 xp)
Strength: 9
Agility: 30
Skills to attributes: 8
Power Strike: 3
Athletics: 10
Weapon Master: 10
Crossbow: 189
Would shoot whatever STR build before it could do shit. Except it's counters 1h&shield or Hoplite. Cav could also work but I think it would be too easy for him to dodge it.
I hope you see my point. But what stops the STR from taking ranged? Well, the wpf requirement. It would make them not be able to get the full boost from their PD/PT (but xbow might work) and they would have to take away their armour (losing their main advantage) to not get too high wpf loss.
Really, the ranged kiting hit-and-run would make the AGI build best in a duel. Anyone have any counters to this?