Debian is almost the same thing as Ubuntu, since Ubuntu is based on Debian. Really linux comes down to a few preferences, and they are typically these things
1) Shell - what shell do you prefer to use even though BASH is pretty standard
2) Package managers - which one do you like?
3) GUI - Gnome, or KDE, which is it?
4) Bundled apps - do you want a Linux distro that has all the basics, or do you want a stripped down version?
5) kernel - I guess you could even use a distro based on what kernel it uses, but I think that may be a really rare thing to find.
The history of OSes goes back to the 1960s when they first started using Unix at Berkley. I am not counting punch card machines here either, I mean actual OSes. In the early 80s Apple and Microsoft both started making their own OSes but didn't really come up with anything consumers could use until the late 80s early 90s really. Linux came out in the early 90s as did Windows.
Since then all OSes still in use have been upgraded, and updated over the times and they all still have bugs and aren't any where near perfect.
So, really to answer your question, what is it that you want to do with your computer, and what are your preferences? Then maybe we could answer a suggestion of what OS to try out.