This is intended as the first in a series of posts that might help answer the question in the title above.
I do not give a single conclusion and I also recognise that Nokia and Google (as with most companies) will have some fans and some detractors also.
Which of Symbian or Google Chromium OS has the better license?
The answer here will be very subjective, so perhaps I might just direct you to some relevant resources and let you decide.
Nokia 'Symbian' license (EPL) is recognised by the Free Software Foundation
Google 'Chromium OS' license ( BSD*) is recognised by the Free Software Foundation
*The license is, I think, referred to as 'BSD 3 clause' or 'BSD New Version' in the description here.
Where things get a bit interesting is in what constitutes the core OS and what are treated as 'addins' or 'Included Software and Licenses'
Symbian under EPL is so new I have no resources to consult regarding 'addins', but for Google Chromium OS this list seems to explain things clearly.
Advocates of Free and Open Source Software would ideally, I think, have both of these projects licensed under GPL instead, and there will, I am sure, be a healthy debate about how each of the chosen licenses is imperfect.
Note: By saying 'recognised by the Free Software Foundation' in the previous paragraphs I hope not to have given the impression that either the EPL or BSD licenses are superior or some 'gold standard'. In some aspects EPL and BSD come out less favourably than the GPL, which would allow better cross fertilisation with the huge package code base, already established within GNU/Linux and GNU/kFreeBSD.
(I have not covered Maemo at all in the discussion above so as not to make the comparison a 3 way. Perhaps some readers might think that Maemo vs 'Chromium OS' would be a more important comparison to make....a valid point....more later...)