The Max Caddy/Drolet HeatPro is my recommmendation...the HeatPro being the most bang for the buck there.
The Kuuma is by far the best furnace on the list, but also the most expensive.
The Ashley is an unproven new model by a copy cat cut rate manufacturer.
Napoleon has very little feedback from furnace owners, the little bit that is out there is mostly bad.
The Big Jack is too small, you want a SuperJack, but they are no longer available to the USA (new) so that would be a used purchase only...and they are not the cleanest burners either.
The Clayton, no...just no. Just because it is made from the heaviest gauge metal does no mean it is built the best...much better off with a Yukon. (the Clayton is made by the same company as the Ashley, USSC)