Finding the best value of price and longevity among brands is my goal.  Also finding a vender that wholesales the canvas for making my own would be nice.
 4-6 person size that is suitable for year round southern Appalachian weather.  Weight isn’t a factor since it would be on my own property. More like a quest house kinda deal.

A GP Small is a good size tent. The Swiss command tents are also very nice.
Size?
Budget?

12x12 sounds like a optimal size.  I didn’t set a budget yet but I’d like to stay under 2k.  Im trying to get some recommendations that I can research so I can look at what is the best value.

We have a Davis Tent 16 x 20 for elk hunting which we got a great deal on it because it's got a purple shade to it and wasn't selling well that year. Ideal for 3 cots along the back wall, stove and a table. We've done 4, with the inner two right next to each other but it's tight. The stove area takes up about 1/4 of the tent because we stack wood and it's gets really hot next to the stove. I wouldn't go any smaller than 14 x 16 for four people just because of the area the stove takes up.

My fall/winter hunting tent was made by Montana Canvass.  It is made of a material that is very mildew resistant.  It has a floor.  You want a floor.  I have friends with canvass wall tents and I much prefer my Montana canvass.

Go bigger!  Seriously though, myself and a hunting buddy bought a 16x20 Davis and it is great for 4people and gear, especially if you end up using air mattresses or cots.  With a larger tent you can have room for a stove if you decide and a table to do cooking, prepwork, eat out of the rain, drink and smoke and gamble, etc.

We bought our 16x20 Davis during one of their sales and paid under 2k.  The folks at Davis are also great, give them a call.  They answered all our questions before our purchase and those we have had over the years with use. Our tent is about 9yrs old now and great.

Build a some kind of a raised floor on blocks, then this garage. Add a stove jack, duck tape on screens and windows.  Supposedly lasts for 4 years. Cotton canvas year round in a wet humid climate won't last very well.

I do plan to build a wood floor.
I just spent today assembling my Woodland Mills Bushlander sawmill. I am missing a couple bolts but I plan to fire it up tomorrow once I go through and check all my bolts etc.   By any chance are any of you in my area that have a wall tent?   Not holding my breath but I’d love to see one setup. The tent is nice because there are no permits and speed of setup.  I will most likely do a post and beam setup over the floor and cover with sail cloth.

Montana Canva., buy once cry once.  I have their spike 11 tent 12x12 which I used as a hunting base camp, it's 63 lb. with fly.  if it were 10 ox. canvas it'd be at least. 100.