Well, I am not particularly confident in my design or construction skills, so I went with a prefab for both the first coop (after getting chicks on impulse) and for my second, more permanent coop.
First coop was the metal-framed
Tractor Supply 6 chicken (hah!) coop that it seems like everyone starts with! Mine is currently disassembled for a deep clean and repaint. I was more or less okay with it, as a starter, but it definitely did not have *roost room* for 6 full-size chickens. It actually had enough space for them to huddle together and stay warm, and they only ever used 1 of the 3 nesting boxes. I'd like to see a prefab that size with more roost space, but only a couple of nest boxes.
This coop was reasonably sturdy, and I did not have any problems with predator break-in, even when we got the crazy dog who deconstructs chain link and opens clips. The metal frame seems to work well. I did not do much reinforcement; my big mods were putting in a new roost bar, and adding some automatic doors (one to the run from the coop, one out of the run.)
My second coop is the Jumbo OverEZ coop, and I do love it! However, shipping ended up being expensive as well as difficult. It came on not one but two oversized, extremely heavy pallets. I'm a single woman, my only assistance was my elderly father, and we did not have a big enough vehicle. That means getting the pieces to my home was a Very Bad Experience.
I used mis-tint interior/exterior paint to go over the inside before assembly, and I'm very glad I did, despite the huge time-sink. It is a solid coop built of 2x4s and OSB, but I think the unfinished interior would have been vulnerable to moisture. I put down vinyl roll flooring, which releases poop nicely. I haven't yet added hardware cloth over the windows- the ordinary window screens are the only security 'weak point' I worry about. The chicken door is a non-standard size, which is great for getting the birds in and out, but terrible for putting an automatic door on it. So, I'd say it is well-made, but still requires additional work to make it a *good* coop experience, just like a lot of the big box store ones do.
Some nestboxes have been repurposed to hold food, water, or supplements. I have 10 hens and 1 roo- they absolutely do not need the dozen boxes. I think that given a large enough run, the coop would comfortably accommodate 24 standard chickens, but I'm not sure how well 30 (advertised limit) would do, which means that again: more nest boxes than absolutely necessary for roost space.