I haven't used one but I have read mixed reviews here on the ones that are made of fir wood. It seems like people that have a fenced in yard do ok with them if they replace the latches with sturdy, predator proof ones and really make sure everything is tight and secure. If you're in an area with a lot of predators, they seem to be a real challenge.
Other types like fiberglass, plastic, and more durable wood sound like they are well-liked and just a personal preference based on affordability and desired options.
If you know a specific one you're interested in, you can search the name of it here and see if there are reviews or posts about it maybe. I do know most people have said the amount of chickens the pre-fabs say they can house is usually over-estimated. Like if it says it can house 6, it may really be good for 4.
Just some thoughts from when I've been hunting around on the topic.