1. Ubuntu (for their excellent work at promoting Linux to general users)
2. Fedora (for showing the perfect business model for Open Source)
3. Linux Mint (because it just works)
Honourable mentions would include Knoppix (a must in any IT help desk toolbox), Symbian (for successfully trying to get Gentoo to the general public), DSL and Puppy Linux (for showing just how small the OS can be), Maemo (for their work with Nokia on bringing Linux to PDAs and cell phones, Android (the true iPhone killer), and the hard workers on the Gnome and KDE projects for showing that Linux can look better then Windows.