As per @woftam, bottom line "Get er done". For me, there's also a "fun factor". This is a combination of accuracy, ease of process, etc. I prefer by weight. Less "mus fuss" by dripping right out of the flavor bottles into a flask while watching the weight. Accuracy is pretty darn close although a drop is a drop. Always some variance. When I'm done, I simply put the scale on the shelf, the flavors in the fridge, and the one pipette for nic I do have to wash and dry. Pretty nice clean up.