Why would you only want to plant one type of tree? I would suggest you plant several different types of trees the same as a real forest. Then you will have several types of wood and if one species doesn’t do well, you have others to take its place. With five acres you have room for a lot of diversity. I would suggest ash like you say, hickory, cherry, black locust and even some pine. If you are doing this exclusively for firewood I would definitely plant black locust. I may even do an acre of fast growing poplar. It may not make the best wood but it would give you wood faster while you are waiting for the other trees to get big enough.