There are many variables to consider.
Are you trying to do everything with one saw or do you have several different sizes of saws? If you can only have one, 50 or 60cc is probably the range to be in.
What is the average trunk size of the trees you are felling and processing ? That right there will help determine how big your saw needs to be.
If you are mobile and doing tons of limbing, then lighter will matter more. If you are relatively stationary and more or less in the cut in bigger stuff most of the time, then weight won't matter as much, because the weight is supported by the cutting bar during the cut.
Yep many considerations for sure.