To the OP; the choice between Debian and Ubuntu could depend on your experience and curiosity to get "under-the-hood" to see how things work. Ubuntu is a "civilized" derivative of Debian, the software is a bit more polished (as in easier to get set-up and running) and "cutting edge" compared to Debian which takes a very conservative approach to releases and is harder to get configured and running.
On the plus side there is a much greater library of available software for Debian, and since there's so many developers you can usually play around with the "latest greatest" software out of "testing" or "unstable" which is much closer to the cutting edge than "stable".
So which of those two distros you choose may be dependend upon your level of computer experience and know-how.
I hope this helps