I'll be the devil's advocate and say that late fall/winter is best. Yes, you have to scrape the bark off but it's usually not nearly as big of a deal as you've heard, it shouldn't take hours at all. Hickory and HHB are the worst (and they're not that bad), locust, walnut, and ash pop off easily in the winter. If you cut at a certain time in the late spring, the layer under the bark is mushy earlywood (the spongy stuff in the growth rings,) or with a very thin layer of latewood over it. If you cut it in fall or winter, there will be a fully mature layer of solid latewood. Also, the wood is more stable and less likely to warp and check when winter-cut than when it's running full of sap. With that said, I cut wood any time I get a chance to. You can't always pick your time, and there's no time that you can't cut it.