The best is not always practical. Technically the best crank clear coat is House of Kolors 2 part automotive clear but it's extremely expensive and takes multiple coats. It has a UV blocker and is tough as nails, if a car can take a rock at 70mph your crank banging a rock is a joke. I have it and use it on swimbaits, easier to manage with the joints in the body. If your looking for something a bit more practical, bob smith industries makes a variety of clears. BSI clears are top notch, not too thin not too thick. They allow the possibility for multiple coats without weighing the blanks down. Devcon is ok if you're making them for yourself and thin it a bit so your crank runs true. It's all preference No matter what clear you use, build yourself a drying rack. Head to Wal-Mart and pick up a barbecue rotisserie, around $25. Even if you use a MCU (Moisture Cure Urethane) I suggest a rotating drying rack. MCU is usually a dip and drip clear, although while the baits hang they can drip off more than you want and make the clear coat brittle. If you're going to use a MCU, hold the belly hook hanger with pliers(needle nose) and dunk the crank in back first. When pulling it out of the clear, rotate the bait a bit to allow an even "drip" before placing it on your rotator. This will allow a thicker, even coat without multiple dunks and cure times.
Hope this helps,