in the early 00's it was Mandrake. totally borked my HDD trying to install that and nuked my Windows XP partition in the process. just couldn't wrap my brain around it.
as for recently? Slackware. My Dad uses it but I just couldn't get it working correctly. More than likely it's simply because I did something wrong during install or setup post install. I've installed Gentoo a few times and I currently use NixOS and OpenBSD so I don't think i'm stupid, I just messed up Slackware.