It depends on how you intend to use the saw that would be the determining factor in which one to buy. If you have big trees to cut, buy a big saw, small trees small saw.
I have a Stihl mini boss with a 16" bar for light work, removing branches and small trees. Its a good suburban homeowner type saw.
For the heavy work I have an older Husky SE 66 (66cc) with a 36" bar, and a cast iron cylinder. It has so much compression that I can't hold the saw in one hand and pull the rope with the other, I have to hook my foot through the trigger guard and pull the rope with the saw sitting on the ground. It has an idle like a high end racing dirt bike, very distinctive sound and with a good chisel point chain it barely slows down going through big trees.
Its not a saw you want to work with all day unless you are a big stong person because it weighs a lot.
I've cut down a 4 1/2' diameter oak tree with no problem, and cut a 110' tall pine.
I've owned McCulloughs, craftsmans and poulans too but I'd rate the Husky #1 and Stihl #2
Some features worth considering on any saw would be a chain brake, spark arrester, electronic ignition and a sprocket tipped bar.