Me I take 3 of them to the woods with me in various stages of "worn-outed-ness" and if I can cut with at least 1 of em till I'm tired,...that's a good saw
anything in the 60cc class would be good starting point. then compliment it with a 50cc limbing saw and a 90cc for the big stuff. brand would be a major problem but get pro model saws for ease of parts and working on.