I have a roof-mounted camera. There are a couple of decisions points. One is whether a system needs to be completely wireless, or if you have the ability to run power or ethernet to the location. Another is if you want the video stored locally (bigger up-front cost for a video recorder), or if it is cloud-only (usually a monthly cost).
My setup is a Reolink NVR system, which runs cameras via Power-over-Ethernet. So, I had to go up into the attic and on the roof to run an ethernet cable, which wasn't overly difficult with my house, but could be sketchy for some situations. I like that it runs continuously, I can access the video from everywhere, and I don't have an ongoing cost for data storage. The downside is that it overwrites about every 7 days (I have an 8-camera system) and if the power goes out, oh well. There are multiple camera options.
One additional consideration that I figured out after the fact is that it is good if the camera is protected a bit with an overhang. I ended up using a clear anti-squirrel baffle on a pole!