This topic came up on another forum. I just copied my response from there.
I have carried a chainsaw longer then I can remember it is a must for the things I like to do.
For trail saw I would recommend a Stihl with a 16" blade and 30cc or so motor model. Keeping a trail saw nimble and light is good. Make sure you get a case with it. That being said I have 2 homelites for trail saw duty or whatever duty that work very well. I have kept them pretty well tuned up, only run non-ethanol gas and have oregon bar and chain on them. I keep wanting to replace them with a Stihl but really have no reason to other then Stihl. I do run a larger Stihl for heavy things but rarely bring it with me because it is to big and heavy for trail duty, camping, etc. I think one of the best kept secrets for me and any saws is keep your chain sharp and keep it out of the dirt I do hate the sound of someone trying to cut timber with a dull chain. So carry at least one extra chain with you. I always have 3 revolving chains, 2 spares and one usually at the saw shop getting sharpened.
Cam-shaft.