They both have their pro's and con's.

I own bows set up with both and after my recent experimentation with blazer vanes through the biscuit I believe I have found a true winning combination.
Those two were made for each other.

In a nutshell, if you like not having your arrow leave the rest accidentally and are in this gig only for hunting then the biscuit will suit you fine.

If your looking for extreme accuracy at any range and out past normal hunting distances
then a drop away may be what your after. Not that the rest in itself provides accuracy, but set up correctly it can help the whole package become more accurate.