Well that depends on what I'm hunting because it takes more arrow to quickly and cleanly kill a large, heavy boned animal than it does for a smaller lighter animal. And I build my arrows to the task at hand instead of the other way around. That being said, I use single bevel 2 blade broadheads at the front of all my hunting arrows (with the exception of very small game arrows).
My brand of choice used to be Tuffheads, but you can't get them anymore, and I'm tired of chasing Sirius Archery as to when they might be back in stock. So it's Abowyer broadheads for me. Awesome quality and a warranty that can't be beat.
For big game like elk and moose I use the 300 gr. Brown Bear because of its superior ability to get the job done when that broadhead happens to hit bone.
For smaller game like caribou, deer, pronghorn, javelina, turkey, I use the 175 gr. Wapiti, for the same reason mentioned above.
And before someone starts lecturing me about making a well placed "perfect" shot, well that goes without saying. Even when the archer does everything perfectly (which is more rare than most will admit) a lot can happen before the arrow hits its mark, most commonly the animal moves. And when that happens, a bone hit is a 50/50 proposition, and I want that broadhead to still be able to do its work.