Of those five I have only used Android and Maemo. On Maemo I would say modRana is the best solution although it has one disadvantage and that is a lack of pre-made map packs. On Android the best I found so far is NavFree. It works completely offline. In fact it does not even have a concept of 'online' as far as I know (haven't used it for nearly a year so things may have changed, I may remember wrongly, etc etc). You download a map for your country and off you go.

Edit: The most recent NavFree reviews are somewhat less favourable so buyer beware. As said, I used it a while ago.