I liked Winamp because it looped audio (when playing a single track on repeat, of course, and if the file was made to loop in the first place) quite nicely (even certain mp3s, I think...this was back in my old ytmnd days so I may just be lying entirely; I know WAVs looped like a charm). Neither VLC nor Windows Media Player really bother to try to loop.* Also for playing around with the various visualizers (AVS, Milkdrop and such).
Granted, I actually got into the player pretty late, and some prefer the older versions for various reasons (less bloat, not AOL, the old skin, etcetcetc). But I liked it and its little about box 3D credits thinger.
*Sometimes I could actually hear the audio loop back for juuuuust so long in WiMP, but then the audio cuts to zero for about as long and the file starts over for real. :/