Hmm, my most-used is WMP, but WinAmp has the best equalizer. Hard to use it while gaming, tho, cuz it's a resource-eater, and it really gets laggy when playing videos.
Strange. My sister bought a really fudged up CD, and my DVD player, DVD+/-RW and my DVD-ROM were all having trouble reading it. Only with WMP could I eek out a relatively skip-free viewing. Not to say I prefer WMP for DVD watching. That's where PowerDVD comes in.