It depends what sound you like.
Originally there were paper cone speakers that have a soft mellow sound, with bright tweeters. i would not go too far back : not before serial numbers of 25000.
I really like these, they have few breakdowns and they are often easy to maintain if problems.
Winchesters are legendary but huge.
Then there was a brief period with polypropelene drivers : only good if you like tight sound without too much base. Maybe need a sub unless one of the top models?
Then there are the carbon fibre driver models, which have a very tight sound.
If you are to buy either the polypropelene or carbion fibre models then you may need soem DIY driver-fixing skills as the glue Castle used often fails. I have several pairs and have had to fix all at least once. Replacement drivers are gold dust, professiional repair extortionate and not really suitable alternative drivers out there.
Recent experience has made me wary of buying / selling by courier. Maybe its just Parcelforce we need to avoid !?