Hello
Theres pro and cons to each. I've either shot two blade or four blade heads so those are two styles I'm familiar with. When penetration is needed, such as larger animals, lower poundage bows and when bone is struck, the two blade works the best. The problem with a 2 blade is that blood trails won't be quite as pronounced. If you make a marginal hit, like the neck or the paunch area, is when you wish you had a couple more blades for increased tissue damage and blood loss.
I shot two bladed heads for years but have of late gone to the four blade Magnus stingers. But now I basically just hunt whitetail deer and the four blade works nicely. One thing about the two blade, if you hit the deer in the boiler room and the blade doesn't hit a rib, often the deer will just flinch a bit like a bee stung it and drop over within sight. Once I thought I'd shot low under a nice buck until his head started dropping lower and lower just before he fell over.
happy hunting
Dan