Thanks for the help guys, I think I've managed to narrow it down to 3 people after looking at FMRTE (I only use it to check CA and PA of players and the Ask Value).
I'm trying to choose between:
Lorenzo De Silvestri
Diego Renan
Gregory Van der Wiel
I have no experience with De Silvestri and won't say anything about him. Diego Renan is good and versatile but on FM10 at least Van der Wiel was a better RB.
Diego Renan - good for backup and can cover multiple positions, quite likely to be the cheaper one too.
Van der Wiel - may cost a bit more, probably the better RB, likely to keep Johnson out of the team once he's settled, but not so versatile.