Get the best you can afford. It might just be me, but I'm finding the more affordable 340mm discs (Pagid, Mintex etc) a little susceptible to warping/runout/whatever it is.
The Brembos should be good, and proper OEM discs from the dealer.
If you fancy something a bit special you can get the 2 piece 340mm Clubsport S discs from Vagbremtechnic. They're 300 odd quid a pair, not sided, and not fully floating (as far as I know), but are probably as good as it gets before you get close to a grand for the likes of AP fully floating discs.