Debian -> Point of Release distribution(Old stable software, meaning only back-ported patches)
Ubuntu -> Point of Release distribution (Newer software than Debian and more frequently updated software, every 6 months)
Arch Linux -> Rolling Release (Bleeding Edge Software, more chances of things breaking because of constantly receiving updates)
If want to run newly GNU/Linux on newly released hardware you are better off with Rolling release, Debian nothing much changes over the life time of a Debian release just patches and security patches and Ubuntu is an in between, the advantage of Ubuntu is that there are many other distributions based off it and there is a huge community of support and alot of software vendors and such also support Ubuntu because it's so popular. All three also have different philosophical standpoints and goals, as well as different user bases.