Gentoo was the "gateway drug" that got me moved over from FreeBSD. I loved FreeBSD ports and Portage scratched that itch with a Linux kernel. Eventually the need for less excitement and a little more predictability caused me to move on. I also miss it at times.
I cut my Linux teeth on Gentoo around when Sabayon Linux was released. Ubuntu didn't make me feel like enough of a hacker, so I had to bash my head against configuring grub through xserver until I felt like I got it. I learned a ton, but it likely wasn't the best use of my time.