i'm surprised to see AIMP getting so many votes. while i appreciate their portable approach, and find the player to be decent, i really hated the library system. it was entirely to rigid for my tastes.
i'm a foobar fan, quite simply because it lets me build the perfect media player. i can make it look and function how i want it to look and function. i'm not into skinning it and making it pretty - i prefer it to look like all the other apps on my system. instead, i go for functionality.
that said, i'm also a fan of media monkey. i love its organizatoinal capabilities, and when i sat down to get all my tags sorted, MM was my tool of choice. but now that my library is neat, i don't have any use for it, since i really don't like it as a player.
i also use Billy from time to time. it's set as my default player, so when i launch a track from my file manager, my foobar playlists don't get disturbed.
my foobar:
http://garbanzox.deviantart.com/art/...rong-119333160