I use PlayerPro. Poweramp is also good, but I have some issue with their player not reading my MP3 tags at all. The tags would have been generated automatically by ripping to iTunes, and I just don't want to go filter through 900 cd's and re-tag/rip them all.
Both have a free trial app, and then a for-purchase app. The for-purchase app provides an equalizer, which I love. They also have downloadable skins, so you can change the look of your player.