Improvements made to the chassis, ride and handling over the past two decades, IVA compatible builds (at least in the UK) have improved the build quality in general and problems that the early replicas had have been addressed (dropped floors, cockpit width, pedal positioning)
Most of these issue can be addressed in the older cars, but cars like the SGT can be built to a far higher quality straight off the shelf.
This is all just my opinion ( having owned 11 GT40 replicas over the last 22 years) but the quality of the SGT offering seems to be trumpeted by all the builders.
I’m UK based so have no knowledge nor experience of other builders elsewhere, this applies (I guess) just to UK cars.
Simon