Dear guys,
I have tried almost all of the media players for Linux out there, and settled down with Songbird for a period of time, till they have completely dropped support for Linux. This meant that I will stick with the same version of Songbird forever, something that I would never consider, since Songbird had its flaws here and there, and I was expecting them to get fixed in later iterations of the product.

To cut a long story short, a brave team took the responsibility of developing a Songbird brother (or sister depending on how you look at it), and ended up calling it Nightingale
So far, I'm loving it. It's much more responsive, consumes much lesser resources, and it's eye candy.

So the question is, what's your favorite media player and why?
If possible, let the discussion revolve around the following criteria:

1- Resources (Memory and CPU usage)
2- Codecs support
3- User Interface ( usability and overall design)
4- Library organization
5- Modularity and expandability (Add-ons library)
VLC. I have been using it exclusively for 4 years now.
I would say the only feature it misses is a proper library organization. But apart from that, it absolutely rocks.

If you're on KDE (and you enjoy having all your apps working together seamlessly, with the Qt goodness and all that), I suggest you take a look at Kaffeine.
vlc is the best media player on linux and arguably also on windows.

http://www.videolan.org/vlc/

it support most codecs and if you can find a codec that is not supported then you can download a plugin for it. it has a big add-ons library

as for the interface, well the best way is to try it... but you cannot ask for a good interface if you care about cpu usage i mean a good design use more cpu... real player is well designed

http://uk.real.com/realplayer/other-versions

but i don't care about it, it's my favorite when i am on xp, but i don't care about it when i work on linux
yup vlc is the best player i've ever used on both linux and windows