Tajue makes a good point....

Wide heads on woods are better served vented.   

I believe Howard Hills book 'Hunting the Hard Way' outlines his findings very clearly.  As far as penetration, concave (curve sunk in) heads were best, followed by straight edge and then convex was last.  He also felt 3 times length to width ratio provided best flight characteristics.

I think straight edge is easiest to sharpen.

I used Zwickey Delta two blade heads (straight edge) for many years and killed a lot of deer and two black bears with them.  Outstanding heads and good value.  Ace heads are also great heads and good value.  A straight edge in one of these two manufacturers is all a bow hunter needs to be successful with a little sharpening acumen.  Learn how to sharpen one of these and put it where it belongs on an animal and you will have great success. 

I like a thicker blade on heads for strength and also the tanto tip or diamond tip like on the Magnus stinger to help prevent tip curl on bone hits.You don't want tip curl !!!

Other than that razor sharp