My first purchase was a carton of 100 Derby's - by far not my favorite choice of blades now, but a good learner. Glad that I didn't find the positive reviews on the Feathers until I had better skills.
Latest (and first) was Personna Lab Blues. I've been at DE shaving for 90 days now. Early on I had success with the lab blues. Lately I've noticed I get a nick with a fresh blade almost every time. Otherwise they perform well. I recently tried Perma-Sharp. They will be the next 100 I buy.
My first 100-blade purchase was Derby. Unlike some people, I actually like Derbys. I get one okay shave followed by 3 really good shaves from a Derby. For me, the 2nd shave on a Derby is about as good as a shave gets, not counting a GSB.
My first 100 blades purchase was Czech made Gillette 7 O clock Super Platinum as I found some NOS at some shop. Actually those were 200. After that BAD bit me and I bought a lot of different varieties of 100 blades.
Astra SPs because I saw them on amazon when I was buying my Merkur 34C back in December. They are still currently my favorite blade which is funny since I bought them blind 😅