I built a "tractor" as my first coop, allll by myself. Nobody told me (ahead of time) that 2x4s are heavy suckers, and so is 3/4 inch plywood. So my "tractor" is a permanent A-Frame coop - I cannot move it. I've since built a more traditional coop - four walls, a roof, all one "floor" - and find it's much more efficient for a whole lot of reasons important to ME.
A-Frame:
Not a lot of head room in the upstairs portion of the tractor for chickens to be able to roost. Door on the downstairs into the pen area needs to be big enough for person to get in easily in order to capture chickens on occasion. Even so. slithering on one's belly through chicken poop is not pleasant. There needs to be a solid corner - not just wire all the way around - so the chickens have a safe corner to run to when under attack by predators. They're not smart enough to go to the middle away from all walls.... so that solid wooden corner is imperative. (I have that.)
My A-Frame is currently used by the chickens as a hang-out, downstairs, especially during rainy days. The upstairs nest boxes are used by the layers, but nobody stays in the A-Frame at night - they all go to other coops. I did use it as Broody Segregation, when a hen went broody in one of the nest boxes. That was useful.
And it's a good "grow out" coop for adolescent chickens, because they can be sequestered there, but still visible to others to get to know each other through the wire without injury as they get bigger. Once they're released from it weeks later, the bigger, grown up chickens already "know" them and therefore the pecking order issues are far diminished.
With a traditional, box style coop, square or rectangular, the interior space is much more easily utilized. Better options for roost bars, easier to clear (in my opinion), no slanted "hatches" to leak in rainy weather, and physical access is far improved (if the coop is tall enough for a person to walk into, even crouched). And a permanent installation is easier to secure against predators, too.
AND, it's a whole lot easier to hang or display cute coop signs on vertical walls!