I have a Stihl and was told by the salesman to get the smallest I could get away with to do the job. They can be too heavy to use easily and if you are struggling you are not safe. The smaller ones are cheaper, lighter and use less fuel. And if you are up a ladder!!
In my case I needed a bigger one as some of the trees were over 2' diameter. So I got one with an 18" bar, which did the job fine but is far too big for general lopping. I also have a 10" Black and Decker electric chainsaw. Very light, extremely cheap and economical to run so almost effortless to use and is now coming up to 35 years old. I could do with something in-between, but an electrical one for cutting near the house for burning lengths is ideal.
So what I am saying I suppose WhiteHorses, is that you may need two three to cover all the jobs.