Based on your three selections, I'm guessing you're in a price range that whatever you end up with, will need some work. A boat that old will leak. Somewhere, somehow, over time the stresses take their toll on hatches, windows, and especially teak decks. If the PO kept after all the leaks as they appeared, you may be OK, but expect to keep up the vigil.
All the systems, engines, fuel tanks, wiring, electronics, fixtures, pumps, etc will be pretty old by now and either have been replaced, or will need it. Of those, engines and fuel tanks are probably the most expensive to fix. A good survey is a must.
Now that I've calibrated your expectations, I can say from personal experience that the Prairies were built like tanks. They did not have teak decks, although quite a bit of brightwork inside. I don't have the personal experience with the other two, so I won't comment.