Nokia N97 has a battery rated for 32 hours of music playback. Enough if you ask me, charge it overnight when you go to sleep and your battery will NEVER run out unless you are browsing/watching video's for over 4 hours a day...Battery life. Weight. Space. Robustness.
I have a creative zen stone 4gb, tiny little thing and nice enough.
Cowon D2 - 8gb + SD Expansion Slot.
Ipods are pretty much as good as it gets without spending mega money, you could always get over your fanboyism or whatever silly problem you have with apple and just get an ipod.
Sony NWZ-S639F
Great audio quality, has enough power to drive 'respectable' cans and a 40 hour battery life to boot.