I have A*'s, RST, and Sidi.
I would rank them but they are all of different in levels of protection/ price point.
A* Supertech R - Best boot on the market imo. Comfy like house slippers and have the most protection out of all the boots I have. Can't go wrong with MotoGP level of protection.
RST Pro Series Race - In between the Supertech and the Sidi's. No internal boot for additional support. Haven't used these yet so feedback limited. Felt ok when I wore them around the house. Bought with the intention of taking some of the load off of my Supertech R's on track. Riders Discount had/has a blowout sale on these, couldn't say no as my RST suit and gloves have survived multiple crashes.
Sidi (I think they are fusions) - First real boot I bought. Did me very well over the last 5 years on the street. Soles have worn since then and I really don't wear them anymore. However I have more than gotten my money out of them. Easy on and easy off, which is nice when street riding. Besides scratches, and worn toe sliders these things had withstood the test of time.