FIRSTLY, I DITCHED REAL PLAYER, ITUNES AND QUICKTIME PLAYER ALONG WITH WINAMP, QUINTESSENTIAL PLAYER AND MUSIC MATCH JUKEBOX - THEY SUCK TO THE CORE.
Then I moved to open source alternatives(excluding fb2k, super)), and these are my best bets. The VLC I use is the latest release, and the MPLayer I use is the one from MediaCoder or the one with the SMPlayer installer, while my Media Player Classic comes from k-lite codec pak.
Most being Open Source, I only wish someone can combine them all, none is perfect.
The Programs Reviewed here(with links to the website for download)
1. SUPER ©
2. VLC Media Player
3. SMPLayer, MPlayer and MPUI
4. Media Player Classic
5. Songbird
6. foobar2000
1. VLC Media Player
needs no facts. you are here anyway... it plays most of the formats well, and is full of enhancements. If you are the geeky sort, this is for you due to the fact that its opensource, meaning you can show off yo your friends all the modifications you made to your media player.
vlc also uses less ram, lesser than MPUI mostly, but usually not lesser than mplayer.exe. It has several advanced functions to make it rock, its the only one with visualisations and EQ, along with gui transcoding. But its interface is horrible. some mov files http://www.drummerworld.com/Videos/john ... bydick.mov play with two windows, one for video and the main window with the first frame. the wallpaper mode is also a bit twitchy, and so is the EQ. This is not yet 1.0, but it still rocks.
UPDATE: VLC 0.9 uses the QT4 interface, it rocks...
2. MPlayer + SMPlayer + MPUI
Useful in playing files VLC can't handle, due to the presence of a methord to use binary win32 codecs. MPUI is the best gui for MPlayer, don't go with the offitial gmplayer. Use it to play real media, voxware, etc.
uses the least ram of the three, and MPUI rocks. but it lacks some of the functionality of VLC and MPC. I assoiated mp3, acc, wma and ogg, wav and other audio files with the non gui version, and it loads in seconds, and the file info and keyboard functions are all awssome, and it uses terrifically less ram. I use MPUI to play long videos, or a list of files while my comp is already chocked in ram due to any transcoding stuff going on. I also noticed - some flvs play on MPlayer, and others on VLC and the rest (all) on MPC....
UPDATE: use SMPlayer instead. It has lots of advanced functions and is comparable to VLC in features. Now I can say MPUI sucks, but there is still the fact that this tiny ~250 kb program can automatically detect where MPlayer is located, so you can keep it in the desktop always. SMPlayer can be compiled for linux, but binaries are available only for windows. It has a nice GUI with good icons.
3. SUPER(win)
A program for windows to encode files even to animated gifs! SUPER ©
it is actually a frontend to MPlayer, MEncoder, FFMPEG, FFMPEG2theora, producer, etc. it is one of the best software for all your transcoading needs. But it can also be used as a player. It even supports DirectShow for the files its internal codecs can't handle.
4. foobar2000(win)
It is a player for the geeky. It is a do it yourself type player, so you need to download plugins to add some compatabilities, and the gui is prettyboring, you need to customize it yourself, but the level that can be achieved through customization is very high, you can even add support for visualizations. This too is a good tool to be shown off. You can enhance it easily, provided you pass its learning curve. If you work well, you can make it look better than one of those expencive jukeboxes used in parties, radiostations, etc. You can even add visualizations. It is highly advanced, with high quality audio output, and a host of other features. the player in its core is propiatary, but its software developement kit is under BSD liscence, meaning that you can make a big adon for foobar2000 and end up selling it for 100 bucks...(I strongly discourage that). But if you are a no fuss guy, forget foobar2000, its not for you.
the standard GUI
somebody's modified gui
5. Media Player Classic(win)
The Best Direct Show based media player for windows. Period.
with the same old school stripped down look of WMP6.4, and completly portable, this is the only player you need to use in case you installed a codec pack.
MPC can play anything, but it uses more ram than vlc. It is the only one which can play Real media comfortably, with seeking. but it lacks an EQ, and other stuff in VLC. the best thing about this is that it can store data in a ini file, and i can use it along with autorun commands to create gift cds with playlist intact. it is also future prooof with new direct show filters made every month. the best part is that the playlist can be put in the same window along with video and audio, I hate seperate windows for playlist, clip info, audio/controls and video.
6. Songbird
It is the upcoming rival to iTunes, and guess what? it is based on the VLC plugin and the Firefox engine. Cool!!!!! but too bad its still 0.2.5. just wait for the 1.0 version to get released! It combines a digital jukebox, an all in one media player and a webbrowser in one software. it supports firefox addons too. it even has skins sorry feathers. it can also retrieve videos from webpages. and you dont at all need a player's plugin, if you have THIS baby.
So What would do you think is better to use? one? or two? all?
PS: I Can't wait for songbird 1.0
) (still experimental), VLC doesn't 
for a long time now and after switching to VLC I've notice a large difference in performance/quality. It uses a little less memory but it definitely has the least amount of CPU usage of all the media players I've used thus far (Window media player, Creative media source, PowerDVD, Nero Showtime, Media player Classic, TrueCast player, QuickTime).
No seriously. 
[joking]