I'm a fan of old Stihl saws so here would be my list. If I were a fan of newer Stihl saws, Husqvarnas, Echos, Jreds, ect, the models would be different but the displacements would probably be about the same.
2 saw
026 with 16" bar
046 with 25" bar.
*I would make an exception here (in all categories) for a newer saw if it were an MS261 with either a 16" or 18" bar.
3 saw -
026 and 036 both with 18" bars
064 or 066 with 28" bar
4 saw -
026 18" bar
036 saws 18" bar
036 with 18" bar, dual spikes, and a full wrap handle.
064/066 with 28" bar.
5 and 6 saw
Duplicating the 026 and then the 064/066 for backup/spare.
Reasoning -
026 and MS 261 - 50cc saws are light weight and easy to buck most firewood with. MS261 is a noticeable step up in power and can more easily pully the 18" bar. As the years go by, and the body goes down hill, these saws become a better and better option for all around use.
036 - 60cc saws are more than enough power to pull an 18" bar which is plenty long enough for firewood. Drop the rakers to make the chain grabby, keep it sharp, and run at least an 8 pin rim. One of the best all around options for bucking firewood. Heavier than 50cc saws, but the extra weight is worth the penalty because it comes with more useable power for bucking and felling. For me, 60cc is enough to efficiently drop most of my firewood trees (mostly hickory) that are in the 24" range, but the saw is still light enough to be relatively nimble in use. 60cc is also a faster, and therefore safer option for felling most trees without having to go as heavy as a 70cc saw where fatigue can become a factor when you're going to fell a dozen trees or more. A 2nd saw in this range makes for a good backup which is useful if it's your primary work horse. Setup the spare saw more for bucking (ie leave the rakers stock, full wrap handle, duel bucking spikes). An added benefit here is that when you reach for your felling saw, the chain won't be dull from bucking up the last tree.
046 - Light weight mid 70s cc saw with plenty of power to pull a 25" bar to quickly buck large rounds and/or fell bigger trees. A substantial step up from a 50cc saw. Big enough to handle anything someone would want to cut into firewood, and also big enough to be an effective for noodling big stuff quickly. Personally, I think it can get to be a bit heavy if I'm felling a lot of trees, but if I'm only doing a few, or even just one bigger tree its fine. While a noticeable step up from 60cc, I'd opt for a bigger step up if I already have something in the 60cc range.
064/066 - 90cc is more than enough power to do anything you would ever need, and more than enough power to easily pull a 28" bar. Not a saw that I want to spend much time felling with, but for the occasional big tree that HAS to come down, the 16 lb power head is still manageable. A 90cc saw makes short work of logs that are over 24" whether its bucking them into rounds or noodling the rounds down into something more manageable.
