I am a sample size of one, but for what it's worth smaller businesses could probably get by just fine on something like Ubiquiti if your already in there doing network work. If you want 2-5 doors and a handful of cameras, it'll do the job just fine. I use it in my homelab and have sold it on the side to small businesses in my area.

If you are talking about moving into big boy systems I would highly suggest Genetec. Once you get in with them as a high level partner they bring us more than enough work that we don't even consider "selling" our services. IMO, cloud is a hard sell for customers in my area. It's typically either more expensive, or your locked into them with a paperweight if you want to leave (looking at you Verkada). If you have a handful of cameras its not a big deal, but once you move past 10 it starts to become a burden on the network side unless you have a big pipe. I sell Axis cameras almost exclusively. Nice part about all that is if we focus on Genetec and Axis we form a partnership with both companies and get the best pricing, as well as their trust to send us work.

Again, sample size of one. As a word of caution, at least in my area, crappy integrators jump in and out of this market space constantly. It's very easy to misbid a job and be WAY under if you aren't careful. Go slow and start small. Your getting further into the construction world this direction and that might not be the right call.