Whichever brand you choose to go with, the price increase from a medium to a large stove is not that great a percentage of the overall cost of installing a wood stove. You also may find you are surprised at how little time it takes to burn 24/7, and how seldom you have to refill the firebox or attend the stove, and may find yourself after the first season of burning wanting to do so(burn 24/7) at some point. I'd get a stove that would be capable of doing that, so I'd go with a large firebox, The medium stoves at relatively high output produce under 40,000 BTU for the most part. For instance, the Woodstock Fireview is rated 44,000 BTU upper limit, 14,000 low burn, with about a 2.3 cu ft firebox, while the PH with dual burn technologies, a larger viewing window (a very rewarding feature) amd a 2.6 cu foot firebox is rated tp 80,000 BTU, with an even lower available low burn of slightly over 11,000 BTU. So, if my heat load was 50,000 and I dec ided to go with a Woodstock, I;d go with a PH, knowing it would meet any needs I ever had.
Don't know when you are actually going to be installing your stove, but if not til after this burn season, keep an eye on this thread for comments on the new stoves coming out this year. Also most stoves are on sale after the burn season. And Woodstock has announced that they have a new stove that they will be revealing late this year that will be ready for the next burning season that is a departure from any stove they have designed before, so that may be worth watching for if you are not burning til next year.
Although, for your build, you'll probably want to know if you want 6 or 8 inch chimney.
By the way, you don't look like you are really a corner install. PH rear clearance is 6 or 7 inches, and it can be top vented, comes with a great cooktop under the soapstone top...