It all depends but a good general rule is buy a stihl.

If it will be used for cutting firewood or more than the average homeowner, get a stihl. Something in the 18" is a good universal length.

If it will be rarely used then something else might work.

I have a MS251 with 18" bar. It was probably in the $300-$350 price range. I have cut down several hundred trees with it (probably in the 700-800 range) while clearing cedar trees and clearing fence rows. There are advantages to buying a stihl (or echo) and you can buy parts for them. My huskavarna saw that I had before worked fine for a short while until i needed parts. Many of the cheaper saws are literally throw away.

Never ever use ethanol laced fuel as you will have problems with it. Just don't ever do it.