40mm drop will be the optimum for handling and sporty look.
Any more will be a pain in the arse over speedbumps and would ruin the handling on Britains rough bumpy roads.
If you can handle your car scraping on speedbumps, struggling to get on the ramps at the MOT station, etc, etc then go for the 60mm + drop, but if I was using the car every day it would soon cheese me off.