I've used them all, I have a 50cc Jonsered with 18" bar that works good for firewood cutting and whatnot. My first say was a POS McCullock 38cc crap I got for about $250 from Canadian tire, never ran well and was underpowered.
Really you get what you pay for, and there is a huge difference between regular saws and heavyduty/industrial saws.
honestly most people don't need the $800 heavyduty saw but they are nice to have, less problems, faster cutting. If you can get a bigger saw for a few more bucks, I think the 50cc range (light industrial) is really the minimum