Define "keeper"
What do you mean by a keeper? Are you a garage full of old saws that barely get used collector, or just want saws to go out and cut wood with, or what?
Any of them that run will cut wood, like any other saw, just size to situation. The older magnesium cased saws are being salvaged and restored/repaired on a daily basis around here, and several members are using the newer plastic ones regularly as well.
Yesterday and today I walked into the woodlot here (way too muddy for the tractor) and felled several pretty decent sized oaks, and then some smaller dogwoods and hickories. I'm working on finishing my 2014-15 wood now.
Used an older 245A which sucks mix but *gets the job done*. It's considered a collector saw, yet it is still quite functional and happens to be my "large saw" and what I use for big trees now. I collect working tools, that's it. And I certainly didn't pay a running/good shape used price like you would for a stihl or husky of similar ccs. Not even remotely close.....which is pretty nifty if ya ask me. And my wood isn't complaining "wah..you didn't cut me down with a stihlavarna 845xpabc magnum II with the built in GPS enabled heated cupholders"!
So, to answer your question directly, to get the full skinny, look up above in the stickies there is an all poulan thread, skim through there you'll see a lot of the models sought after. ya, it is a real long thread, but you can skim it and see what is what pretty quickly, plus see good pics of the various cool models.
Bottom line is, older mag cased, worth it if cheap (to you, depending on why you want one), the more modern ones, still worth it if cheap (to you, depending on why you might want one) and don't have scored pistons or cylinders.
