Selling Would Be a Mistake!
It is very difficult to convey to someone outside this hobby just how huge the difference is between vintage machines and new ones, but I'm going to try.
- Working parts that used to be metal - for good reason - are often now plastic.
- Functions that used to be controlled by sturdy mechanical timers that lasted for decades are now controlled by electronic boards that are vulnerable to power surges and moisture (not like a washer produces any of that, huh?). Google "washing machine control board" for a wealth of horror stories about boards that blew, either costing a bunch of money to replace, or being irreplaceable because they're discontinued already.
- Settings that used to be controlled completely by the user are now controlled partly by the machine, in the name of energy and water savings. You can't get a true hot wash, because a thermostatically controlled valve in new machines sees to it that you cannot. Water levels are much lower than they used to be on most machines, with the result that clothes can't get as clean.
- These machines have already lasted thirty-five years, and with maintenance, could last thirty-five more. Many new machines don't make it five years.
I cannot tell you what is best for your situation, but I can tell you that a vintage machine, properly maintained, will outlast and outclean most any new machine out there. If you keep these machines and take care of them, you will have satisfaction that will last wayyyyyyy longer than the little bit of money you will get from selling them.