The problem with all of these "best of" threads, is that all you will get is a "most common" thread. Lots of people will vote for iPod because they are so common, whereas iPods aren't necessarily the best.
Personally I would prefer an iRiver because you can drag and drop music onto it, it plays WMA and OGG files, has a much better battery life and has a remote with a display.
Its all irrelevant anyway as I can't afford one
So just be careful what you are asking. Not many people will have tried lots of different players