Ask Slashdot: what is the best distro for linux lessons?

MBtronics writes: I work at an embedded hardware/software company and we are currently moving all our products for Windows CE to linux. Our core development team already uses their favourite distro for development, but the rest of the developers is still working on Windows. We are going to give a series of linux lessons (from 'what is linux' to installing, using and developing) for everybody in the company who is interested (including non-developers). They will be allowed to choose their own distro, but we will certainly get the question which one is recommended. My question to the slashdot-crowd: what distro (and windowmanager) do you think is the best to teach a generic public linux? We are currently thinking of Ubuntu, Fedora or Mint.