Slackware seemed the most mature at the time I started. Also, I really liked the way they split the packages into directories. I could just download the things I needed in one go. When you only have access to dial up, having to download stuff during installation is painful. So, I’d download all I needed over the course of a couple days, then I’d install it with all the needed stuff already in there.

After I got more used to how things worked, I eventually moved towards Redhat until I finally landed on Debian.