Whatever Ubuntu was available in 2015. I only dabbled in Linux over the past 10 years. More seriously switching over in the last year or so.
I have Unraid as a server OS (Debian based, running a lot of docker containers and a couple VMs). Debian on my laptop. And Bazzite (fedora based) on my Lenovo Legion Go.
Still need to swap my gaming PC from windows. May try Bazzite on that as well. I've also tried Mint, Manjaro, and Zorin
Yea I'm running a much leaner Debian on my laptop now. Base OS was very bare, slowly adding only what I need because it's a 2016 laptop and noticeably slower on some more bloated OSs