I installed pop!_os as my daily driver some months ago (completely got rid of windows) and have thought it pretty good. But something about it seemed off - it would take programs just too long to open, it wasn't snappy... Once I got into something it seemed to run fine (playing dota or something else was fine after initial quirks).
Well, today, figured it out...
When I did the first install, I was very nervous about deleting all of my existing data on my disks and so tried to manually partition everything so that I could get it right (I think I was also planning to dual-boot).
Fast forward to today, and I'm testing speeds on all the drives to see which one to pitch for a new one I acquired. I see the 3 HDDs, but where is the SSD... Oh god, I installed the boot partition and root and home all onto one of the ~12 year old HDDs and the SSD has been sitting idle.
Anyway, just about done with the new fresh install onto the SSD, hopefully it isn't too hard to start port over the home directory from that HDD...
Yeah maybe I got so used to SSD's that I can't remember the leap between SSD's and HDD's.
An as you said the difference between M.2 isn't that much of a difference in game. There probably lies my bias.