Which Ulm national units should I recruit?

[Zooko]

Yeah, these charts show that Black Plate Flails are significantly better than the other infantry.

[BigDaddy]

They get 2 attacks.

[BigDaddy]

I strongly recomend using good sized groups of crossbows guarded by small groups of black plate flails to take independent provinces.

Don't overlook the Lord Guardian, he is one of the best trained units (high base scores) you can recruit, and benefits greatly from equipment.