some of the clones claim much better battery life than ipod, but at the end of the day, my opinion is that the ipod is better enough to justify the extra cost. Its a darn good music player.
I use iTunes to create playlists and manage music (i.e. there are no players to hold 90GB at present, iTunes would help you manage what you want to put on).
Smart playlists (i.e. auto make a playlist of xyzGB or xyzMinutes, play me songs that are 4 or 5 star, have 'rock' in the genre but not 'country rock', and have not been played in 7 days, and are over 2 minutes long but less than 10 minutes, then order them by least often played).