Here's a link for heat yield across several species. I think the absolute best is osage orange. Most of us, however, have to cut whatever grows in the region. Pretty much limited to conifers here.
Firewood BTU yields by speciesSimilar link with a few different listingsChoices here are: Doug fir, Ponderosa pine, Lodgepole pine, Grand fire, Western Juniper, and Larch. We favor Larch because it burns clean (remove ashes once a year), is easy to split, and grows very tall with few limbs and little taper. About like cutting down large telephone poles. Try to get it in by the middle of June to beat the heat and free up the fall for more fun endeavors.
Could probably heat the house for a month with the chopping blocks. The larger blocks are Ponderosa Pine. Hard to split, so they will hold up for several years. Five layers in the shed, and we use about 3 1/2 in an average winter. Lengths are 15 inches, so one can open the door and throw them in the stove. Obviously, I like a tight stack. Have about a 6 year supply outside of the shed.
USFS charges $5 a cord, then we have our labor and equipment costs. We could go about 6 miles and harvest pine, but think it's worth while for ease of cutting and splitting to run about 40 miles for Larch.