On drag/drop versus syncing:
If the choice is between drag/drop and WMP sync, then definitely drag/drop. However, if other tools are an option, then I’d go with syncing. Winamp and MM come to mind. I exclusively sync with Winamp in MSC mode.
If you are more playlist oriented, then syncing makes a lot of sense. You are more into playing whole albums or like browsing for specific tracks, then drag/drop may be simpler.
Another case for syncing would be if you like to keep your player full, but rotate content in and out fairly frequently. Or if you like to be suprised, most syncing tools can fill you your player with random songs, songs with a certain rating, etc.
In either case, I would avoid WMP and MTP mode if possible. If you have DRM content you may not have much choice, but otherwise go for MSC mode and better media management tools.