OpenBSD with tmux
Being able to take off from work, and the next morning, be able to hop back into my tmux session from the day before is truly lifechanging. I used a custom screen config for a little while before stumbling across tmux. I read into tmux one day at work, and was simply amazed at how much easier it was to configure than screen! This led me to conduct an in-depth comparison between tmux and screen. Did you know, screen has some 254 known bugs? Some go back to 2005 the last time I checked.
Tmux is an active project that is significantly easier to configure, and just as stable in my experiance.