Thanks for the comments Lum, and Franco I did the search you suggested
and found Jack Keller's comments from 1999 where their club compared
ports made from both methods. Hope Jack doesn't mind me re-posting part
of his post:

"All of these were relatively young ports, 2-6 years old. In
my opinion, the port made without brandy had a much deeper and richer
flavor, while the ports made with brandy fortification were fruitier,
more complex and somewhat more interesting."

Not sure from this which style he actually preferred. Maybe Jack will
see this and comment more.