I'm using Media Monkey, works great. I like the ability to only sync certain playlists and such. It really works great to keep only current music, or music you have rated and such.
Media Monkey is worth the price! A couple years ago, I was looking for a media manager, and tried itunes to have it completely mess up my library of music, renaming folders to the incorrect artists, reorganizing disks, shortening the names, etc... Media Monkey came to the rescue to fix what itunes destroyed!