I'm not making firewood but have had to clear away a few fallen trees and major branches over the years. None had a particularly large diameter truck, so was able to use my remington electric (corded) pole saw that has a detachable standalone chain saw. It's around a 10"-12" bar.
Since it's a pole saw, it is handier than getting out a ladder too, to use my cordless recip saw, but I do use the recip saw for anything on the ground that's about 3" diameter or smaller, and far more regularly for trimming my otherwise, formerly/long ago overgrown, bushes.
The recip saw gets into tight areas that a chainsaw can't. I have a pruning blade for it but if it's just a quick one-off cut or two, I'll just use the regular wood blade I leave in it, don't even bother to switch it to orbital mode.