Elite Cavalry and Knightly Heater are both the best.
Really fast so you don't have to raise your shield whenever you are not attacking and decent amount of resistance and hit points. And they both look awesome :D
Yes, I just think Knightly Heater Shield has more body armor, from 25 to 35. In the duel, it is more advantage.
At +3 and 5 skill this shield is basically unbreakable and you have much more time to pick your shots while under pressure.
Heavy round shield.
Almost as large as Husc, and nearly as tough, but a good bit faster at MW.
I run with 7 shield and this shield and it is almost as fast as knightly heater, but allows me to fight 3-4 enemies at once and hold the front line charge.
So long as you are a good at blocking, and have quick reflexes, the speed shouldn't matter too much. I only have 4 shield skill and it isn't too slow. The best part is it never breaks, even when taking on several guys like Konrax said.
I also used the Hand Pavise Shield, in addition to size, they are almost right.
There hasn't been a point in time where the Elite cavalry shield isn't clearly the best shield. But I like the new Brown lion heater, lighter version of elite cav.