subject tells it all. their both the same amount of money but 1 has body armor and one is alot faster.
As far as absorbing damage, the plate shield is better at everything but shield breakers. The Knightly kite may be
slightly better against shield breakers.
However, you shouldn't use either shield against shield breakers. Put it away and manual block in those situations.
Regarding speed, there's a big difference between 75 and 100.
A 75 speed shield doesn't block until AFTER the shield is all the way up unless you have a high shield skill. A 100 speed shield blocks BEFORE the shield is all the way up. You can tap blocks with a 100 speed shield.