The Harmon doesn't have a mitton dryer.
Tough call, but I'd bet the Harmon does a better job with a bit less work. The Vermont Casting does look to have a longer flame path, maybe get's a bit more heat out of it per pound of coal? But, that flame path makes a place for ash to collect & needs to be cleane dout now & then. You can load the Vermont from the top, and also the exhaust can be changed from out the back to out the top if that's a help to you.
The Harmon looks a bit deeper & less wide. Coal likes deep.
Maybe it would come down to price & looks. If you like the style of one over the other, or there's a big price difference, get the one you like.
I had a VC for a week. Sold it to a friend. It's all cast iron and well built. He hasn't fired it yet.
I'd be betwizzled to pick between them! OK, Iv'e decided... get the Harmon.