My first was a Glock 21. I decided I did not like it because of the huge size and poor ergonomics.
After that I tried several revolvers: 6" Smith & Wesson 66, 4" Ruger GP100, 6" Ruger GP100, 4" Smith & Wesson 686, and a Smith & Wesson 642. I decided I do not like revolvers because of the weight and long double action trigger pull.
After that I thought the 1911 would be perfect based on the reputation for excellent triggers. After two Kimbers and two Colts, 4 1911s in total, I decided I do not like 1911s because of the weight.
After that I thought a polymer gun would be the way to go. After my experience with the Glock 21, I wanted to try something smaller and more ergonomic. I bought a Smith & Wesson M&P Compact in .40 S&W. I decided I did not like it because of the way .40 S&W recoils.
After that I bought a Smith & Wesson M&P full size in 9mm.
Now I have my first gun. Or at least, the first gun I want to keep.
(Well, to be technical I still have my Smith & Wesson 642. I don't enjoy shooting that little pocket rocket, but having a gun that I can conceal in almost any clothing is too good to sell.)
It only took me 12 (yes, twelve) tries.