Just joined and thought I would start with DE blades. Interesting mix of preferences.
Tend away from blades from Russia and cheaper blades just to avoid spending money for something I'll end up regretting. Tossed a crate of Astras for instance. Ran through a big box of Dorco to little benefit overall. My test is state of my beard 10 hours after shaving. Most blades fail that test.
I have a light beard, shave daily and change blades between 4 to 7 days. I use Muhle Grande R89 from a really excellent shaving supply shop (not UK). I am happy with Merkur, Muhle, US Personnas and Timor. I think good prep is critical to blade performance as much as blade design, for a mass-produced but precision product, that is.