The advice I was given was if you read music get an English because It's more logical ie notes between the lines on the right hand side and notes on the lines on the left hand side. And only one note per button. The advice I would give is get one with a good range. The first concertina I had was a D/G anglo and like Jets learnt to play some tunes fairly quickly but soon found the limitation of only 2 keys very frustrating especially when accompanying singers.
Make sure you get a good play of both before making up your mind.
Have fun
Baz