I'm refering to Anglos here.
I don't see Norman concertinas mentioned yet. I tried one out at a festival earlier this year and found that it played much better than I expected, particularly for the asking price. if I were looking to buy at the moment I would be chasing more info on these.
Lachenals can be variable in quality, the best of the top models rivaling the best Wheatstones.
Wheatstones have a couple of periods when they were not consistent in quality.
I don't seem to get on with Jeffries concertinas, they don't sound right when I sing with them!
I used to have a Jones for a while and I agree with Dick that the response was slow.