Depends on the particular job at hand. For server use I originally stuck to RHEL based distro's but Ubunutu has become a serious contender due to the built in unprivileged LXC/LXD support (No other distro supports this out of the box to my understanding).
For desktop I'm normally using Arch or Linux Mint (but trying out new distro's can be pretty fun).
What about yourself?
I haven't set anything up yet, just trying to get my head around all the different versions, and how to set them up. I was looking into Ubuntu.