We have tried many brands of poop bags. Some were plastic which would never decompose, others were so biodegradable they ripped when opening them. We finally came across Earth Rated Poop bags which are somewhere in the middle of being plastic and made from biodegradable materials. We usually buy them on Amazon because they have the best price.
Earth Rated Poop bags are owned by a Canadian based company that touts everything they use to produce their products as eco-friendly. Their green-colored bags are made with an additive that allows them to break down easily, unlike plastic bags. I believe I read where it takes about 100 days. They also make a white-colored bag that has no additives which allows them to decompose faster. The bags are scented with a lavender smell that is non-toxic. They do smell pretty darn good for a poop bag!
We buy both the roll and handle bags. We bought a box of 60 roll bags last year and still have a few rolls left. A box of 60 rolls with 15 bags to a roll will last us a year with our two dogs. We usually use about 3-4 of them a day since we walk our dogs in the morning and night. The handle bags are used for backyard poop duty. We use one or two of them a day. We just buy the handle box bags which contain 120 every two months or so.
The box of 60 rolls come with two dispensers that work well. We have had other dispensers that break or cause the roll to get stuck inside. The Earth Rated dispenser doesn't get stuck and works easily. We are still using the same two dispensers that we got a year ago. Earth Rated Poop bags are a keeper!