theyre both pretty damn good if you got good material, good tools and good techniques.
butane is a hair more expensive to make, a hair more dangerous, and maybe a hair less healthy while making, and smoking... BUT, it is more potent.. gotta sacrifice some things for more potency!! as well as a higher yield. BHO is almost like bubble hashs older brother on steroids.. faster, stronger, more weight to it, but harder on the body!!
bubble hash is cheap, safe, easy to make... but your return might be low, as well as the potency a little bit.
me.. im a risk taker, and I like getting really high, as well as getting a 20% return of like 80% THC material. I also dont got the money or bud to be wasting on inefficient runs of bubble hash. (I had 100g yield 7g of bubble has one day... and it was nothing special. same 100g made 18g of killer BHO. cost 50$ in butane though but well worth it!) if I were growing though, and had tons of fresh trim and more bud than I knew what to do with... damn rights id sacrifice some and make some hash.
some guys are happy with their bubble hash runs of 10% return with 60% material.