That Denon app is pretty cool. The audio eq is licensed from elephantcandy, the makers of EQu. I think I'll take sound quality over battery life but I have a touch, not an iPhone so it's okay if It runs low. I love how the Denon app has a queue system, something EQu is missing but EQu sounds a tad bit better to me.
I've tried Equalizer extensively but I just can't get the phenominal sub-bass that I can from EQu, but Equalizer is less battery intensive. Equalizer has a queue system, but the app is buggy overall and crashes on me frequently. Although the dev constantly updates it which is nice.
I've used the BBE app but don't like it at all.
Stereophonic's audio eq is also licensed from elephantcandy but the UI is dreadful.
Seems like I've used a couple other eq apps but can't remember them off the top of my head.
I keep going back to EQu for my eq needs but that Denon app has queuing funtionality so I think I'll try it out for a while and see if it beats out EQu for my needs.