Top things on my helmet list are fit, adjustable vents (I run hot), and some type of fit adjustment harness. The lighter the better. I could care less about audio, cause I think it's far more important to be aware of your surroundings but most manufacturers have some type of audio add on.
That being said, I have grown very found of my Smith Vantage but there's no way I'd pay full price. Pick up last years, or wait for sales and you can find it for 100ish or less.