I feel so old. For me it was anything with TWM and xClock. Slackware and NetBSD come to mind.
Props to the Raspberry Pi desktop folk (for both rpi and pc/mac versions), since they take the LXDE environment and tweak the underlying Debian distro and the desktop environment to kinda' humanize and maybe oversimplify it. That's all it is really, Debian with a customized LXDE to their tastes so that people don't go too gaga over it, and get on with other things.
There is one guy there, who is into the whole Apple usability thing, and tweaks the LXDE to make things a smoother fit to setup without having to do any "drill downs" to get the setup right for non-computer savvy nerds unlike us. Including special fonts and whatnot. Automatic updates yadda yadda...
These days my interests are booting and *running* from fast USB, so I usually stick with the defaults. That way I don't have to bother what's already on the machine, be it a Windows install, or a full Ubuntu install. My "install" is only to a usb drive.
Knoppix 9.1 is one such distro (NEVER update it - just wait for semi-yearly releases). LXDE default, but you can choose among others at boot time - that thing is a kitchen sink!)
Porteus
NomadBSD (for those who like BSD, but still filled with gnu stuff. Makes a groovy usb)
.. and a whole host of others if you don't want to touch your existing install and just want to run from usb when desired...