The traditional view is that the best firewood is from hardwood tree species. In some regions, the hardest species available are oak or maple. A given volume of oak or maple has almost twice the energy content of and produces a longer-lasting fire and hotter bed of charcoal than soft species such as poplar, or willow, so fewer cords would be needed.
Any dry hardwood will work well, but for keeping your chimney clean stay away from pine or other pine type trees that have a heavy pitch/sap content. oak has been a favorite because it is a very dense hot burning wood, that cuts and splits easily. with time you will learn to get a good hot fire burning and then adjust your damper to control the air to give a hot yet long burning fire. birch also burns well but because it is a less dense wood will burn faster (a good fire starter). where efficiency is concerned any hard wood that is dry and you can get it cheap or free, that's what you might want to go for. when I also used elm and boxelder, but they are hard to cut and split. they burn fine once you get it dry though.
But let me offer another take. You will need to run your stove at high output for only two or three months in winter. In spring and fall, you won’t need as much heat or especially long-lasting fires, so you can burn softer wood species during milder weather. Plus, softwood fires don’t overheat the house if you just need to take the chill off in the morning.