I swear by OpenBSD. I use it on my home server. I use it to write C code (their C standard library has a few very nice things, such as arc4random, strl{cat,cpy}, explicit_bzero, timingsafe_memcmp, libtls, and other things that I run into often enough that I don't want to think about them before I start adding portability stuff).

Of course, it's not much of an option for anything I require proprietary software.