PC-BSD (based on FreeBSD) on my laptop works surprisingly nicely. It's been more stable than Xubuntu for me, and because of ZFS, capable of rolling back any wrongful update without an external backup. The ports system is straightforward and close to hand that I already want to contribute. I didn't know such system can be done with just a git cloned hierarchy of dirs with makefiles doing search. While its GUI app manager AppCafe resembles Ubuntu's user-friendliness, if not better.

For server maybe you can give OpenBSD a spin for its fame of security.

I started using freebsd two weeks ago. My usual ruby stack carried over just fine and so far it's kinda fun. The stack being sinatra, thin, nginx, postgresql. I assume any other sane backend stack will carry over just as easily.

The last on battle field are Void Linux, Slackware and Getnoo.

Don't forget Alpine Linux