Best for what ?
I have been studying these stokers for a while, and here are some results I found by actually observing and testing some of these stokers :
The best for burning , would be a harman stoker, but that tend to be on the pricey side, super heavy and bulky, I have noticed however, that spare parts ( blower, grates, etc ) tend to be extremely reasonably priced. By the way , looking at the ashes, gives you an idea how well a stoker would burn, ashes coming from a Harman, don't contain too many black particles ( unburnt coal ).
Keystokers units are great if you will be using the stove in a living area, and like to see those flames, Keystokers have the clean glass system, where part of the blown air is redirected at the front glass, and keeps the glass clear for a long long time, the newer Keystokers, have a close to horizontal burning area, where the efficiency of the burn tend to increase, thus they burn as efficient as the Harman , if not better. Keystokers are pricey too !
The older Alaska type stoves, along with the Reading , have the most reliable and simple mechanism, they use a sliding carpet system, and they have no problem burning wet coal, ( harman, Keystokers and others ) use a push bar and may jam with wet coal. Alaska and reading sold too many so you can always find them on Criagslist. It's also extremly easy to service the Alaska type or make few improvements and modifications.
I can not say much about the Leisure lines stoves or the newer Alaska models, since I haven't had any experinces with them.
I hope this would help.