You have asked opinions in lots of places here. Everyone will have a different opinion. At some point only you can decide what you want to cover and how best to cover it with your budget.
Personally, I would choose a varifocal over a fixed lens in most situations. The fixed lens gives a nice overview, but the first time something happens and you cannot identify, you will wish you had a varifocal that you could zoom in more for the next event.
When we had a thief come thru here and get into a lot of cars, the police couldn't use one video or photo from anyone's system that had fixed 2.8mm or 3.6mm cams - those cams sure looks nice and gives a great wide angle view, but you cannot identify anyone at 15 feet out and at night you cannot even ID someone from 10 feet, especially on auto shutter that so many run cams at
. Meanwhile, the perp didn't come to my house but walked past on the sidewalk at 80 feet from my house and my 2MP varifocal zoomed in to a point at the sidewalk was the money shot for the police that got my neighbors all there stolen stuff back.
In fact my system was the only one that gave them useful information. Not even my other neighbors $1,300 4k Lorex system from Costco provided useful info - the cams just didn't cut it at night. His system wasn't even a year old and after that event has started replacing with cameras he bought from
@EMPIRETECANDY based on my recommendation and seeing my results - fortunately those cams work with the Lorex NVR. He is still shocked a 2MP camera performs better than his 4k cameras... It is all about the amount of light needed and getting the right camera for the right location.
My first few systems were all 2.8mm lens and while the picture looked great in daytime, to identify someone you didn't know is impossible unless they are within 10 feet of the camera, and even then it is tough. You are getting the benefit coming to this site of hearing thoughts from people that have been there/done that.
We all hate to be that guy with a system and something happens and the event demonstrates how poor our system was and then we start the update process. My neighbor with his expensive Lorex fixed lens cam is that guy right now and is still fuming his system failed him.
Main keys are you can't locate too high or chase MP and you need to get the correct camera for the area trying to be covered. A 2.8mm to IDENTIFY someone 40 feet away is the wrong camera regardless of how good the camera is. A 2.8mm camera to IDENTIFY someone within 10 feet is a good choice OR it is an overview camera to see something happened but not be able to identify who. Also, do not chase marketing phrases like ColorVu and Full Color and the like - all cameras need light - simple physics...
The best advice we give is purchase one varifocal camera and test it at each location you want to install a camera and confirm the lens you need.