I would say that John is the most successful, but Guy is my favourite and I love all of his albums, so far. I have tried to like Richard Bennett, but everything sounds very samey. I have a few of the folkey boys albums, including the trio (john McC, Mike McG and John Doyle) and enjoy listening to them now and again. David's music does nothing for me, but I think he is 2nd.
So, John is probably the most successful, David is 2nd, but Guy is my favourite.