I think that by concerntraiting solely on one you lose the benefits of another...
e.g. if you say Linux is best because it has the best web server,
then you miss some of the best games that only come out on windows....
If you say open office is best because you can publish straight to PDF without a third party distiller then you miss out on the version/change tracking features of microsoft office...
I've not yet fuond a clear cut answer as to which is best...
certainly I could not use one solely without loosing some of the vital features another provides...
(I know all of the examples I posted can be imlpemented on each other system, but it's usually badly)