This has been my experience:

Dorco 300s - The blade feels like it is scraping. I do like the sound. It is good for a change of pace. The blade is very economical.

Red IPs - I get 3 good shaves. They are consistly good and well priced.

Derbys - They are inconsistent as hell. Once in a while I will get a great blade that lasts 4 or 5 shaves. Some blades last 2x or 3x. Some blades are bad from the start.

Feathers - Extremely consistent and very sharp. They are priced at a premium, but they last four shaves or more.

Super Iridiums - The best blades I have ever used. They last for 5 shaves or more. I change blades not because they are dull but because I am afraid of getting razor bumps if I use them too long. They are smooth and comfortable. I put it in my tech and it feels like there is no blade in the razor.

Merkurs - They give a comfortable shave. But, I end up with razor bumps all over my face. This happens with a fresh blade.