I have used Feather, Merkur, Astra and Derby Blades. I am currently using Astra Blades in my Merkur Safety Razors. They are excellent, sharp, non irritating and last for many shaves. I find the Merkur Blades to be dull, and last only 3 or 4 shaves at most. The Feather are excellent and comparable to the Astra. I will have to try the Feather Blades again before making that comparison. For the money Astra Blades are a tremendous value--5 Stars easily.
These are the best DE blades I have ever used. Close shave no nicks and I have somewhat sensitive skin
Used them for years---top rate blades.