Okay, lets look at the two you want to keep.
034 as you have read today is getting very hard to find 46mm pistons for if needed- but can be turned into a 48mm Super or 036 fairly easily.
028WB is a Rancher/Farmer model and has a handguard not a chain brake, they are pretty bulletproof- but not ***** proof.
"I had a 391 for just past its warranty but it tore the piston up really bad and I’m still not sure why that one did that, I maintained that saw very well and I’ve never scarred one up like that before, I think it may have been a defect."
Is a bit alarming to read- "not sure why"- but about to dive into some bunch of unknown's for plug and play?
Any Stihl is not cheap to get parts for- well for good parts anyhow.
Need to get them in hand and go through each, decide what us viable and what is not.
034 is the pick of the bunch for what you are likely to be cutting, with the 440 for smaller stuff- but it is likely to need refreshed in all the expendables from main oil seals up- pass pressure and vacuum testing and have good compression and you will have a reliable old saw.