Also check for scrap wood at a furniture factory. Hardhack is considered a trash tree where I live. It's not any good for furniture-making or pulpwood for papermaking, and it grows prolifically. I've never seen a big one. The small ones that I cut when I'm clearing a plot make fine firewood, as the roster indicates.
Apple trees incline to be gnarled and tough when full grown.
You'll have few long lengths to cut and split, and plenty of knots. However, they have almost a pleasant aroma while burning, and you may decide that apple is worth struggling with for that reason. Oak, ash, and maple all split much more easily. If there's a straight stretch of trunk as much as four feet long on either a black walnut or a black cherry tree, you'd be a fool to cut it into firewood. These are highly prized for making furniture veneers, and should be sold to a specialty mill.