Actually there are three available.
Accurate
ADV Azimut 
S-Model
Accurate is apparently best, but needs work, as was said.
I haven't seen the S-Model kit but it is of a late war Mk III and the only one of that model available (although slapping a Crusader III turret plus 75mm barrel on a Stag kit isn't that hard).
Avoid the ADV kit like the plague as it is an abortion. I built one and know whereof I speak! The list of corrections is long and labourious and still leaves some things unfixable.
[cynical rant mode =on]
As for one in styrene, well if the model hobby industry actually lasts until I croak, it'll be long after I die before any will be made by any existing manufacturer.
[cynical rant mode =off]
:-)
Paul