GGG, Canelo, Jacobs, BJS and Jr are the top 5 of the division. GGG is the concensus no1 obviously, some may even bracket him on his own tier above the other 4. BJS has been taking 0's left, right and center. Beating Andy Lee has confirmed him a seat on the top table. Jr is a physical beast who arguabaly has already beaten BJS and a rematch with a probable rubber match is on the cards in the near future. His destruction of highly rated Chudinov and beat down of a very game solid Spike O'sullivan have made has case for the top table hard to argue. Obviously if Cotto fights on he gets dropped down but otherwise he would be a favourite to beat everybody else.
GGG Canelo Jacobs and if he wants it Cotto are the top man. In the UK alone there is at least one middleweight - (Nick Blackwell) who would probably beat both BJS an CEJ today. You know what? Its not impossible that Andy Lee could beat Billy in a rematch - there was nothing in it in the end.
They are top tier British MWs. That's all we know so far. They haven't tested themselves on the world level yet.