With respect.Deep litter, for sure. It’s the easiest and can help the coop stay a bit warmer in winter. You just turn it regularly with a shovel.
Deep litter (ie. composting in place) is virtually impossible in a coop that has a floor; it can be made to work if the coop floor is dirt but still difficult. Moreover, any heat produced will be overcome by winter temperatures and the chickens are well equipped to deal with temperatures into the -30C/-22F.