It has a lot of features,it also can be used to listen radio's.
www.winamp.com

Winamp is just a very widely spread player. It is good for its numerous plugins but I wouldn't excactly say it's the best. It's not a very compact player, there are several other players that perform much faster and use less memory.

VLC is better! it plays more file formats than ANY MP3 or video player

I do not know if Winamp is the best MP3 player but I know for sure that it is the most popular MP3 Player all over.
Windows Media Player and Real Player are also popular.