Playerpro: powerful, great dsp manager, and it supports native HTC sound effects! DSP is great for equalizing music, but for actual sound clarity, SRS and Dolby are the best (same goes for beats, but playerpro doesn't support it)
HTC Sense stock music: awesome with it's equalizer. People say Beats and SRS is over rated, and a dsp manager can make up for it, but in my opinion a DSP by itself is best if you have great headphones and you play high quality music or something. But if you don't (like me), the equalizer options do magic.
MIUI music: best stock sound I've heard, and the equalizer is a nice touch (only 6 bands though, enough for me though)
Noozy: great sound effects, and if you're on CM or if you have a universal DSP manager, then it'll be great. free too.
Zplayer: Pretty much the same as noozy, but apparently noozy was a rip off of it. This one is payed though, but if it's anything like noozy, then it's probably worth it (thanks elpresidente)
Neutron music player: crazy options and effects. It's a little heavier on the battery usage in my opinion, and I'm not pick enough with my music to really need so powerful an app, but if you're an audiophile then you might want to look into this.