Clearly supercars have to have a high sill for structural stiffness and crash safety reasons. Clearly they must be wide and low.

It is funny watching tall men getting in and out of high sill supercars.
There are several youtube videos of newbies trying to seat in a Lotus Elise for the first time.
There's also a funny Top Gear episode of Jeremy Clarkson Ford GT. As its doors have a portion of the roof attached you couldn't easily get in when another car parks a few feet besides you.
So what would be the better way to allow easy access to high sill supercars for daily use?

Attaching part of the roof clearly allows easier entry.

But it would be funny to watch 50+ year old people (usually the kind of people that can afford supercars) opening an unassisted upswinging door like Lambo doors, Gullwings, butterfly.
Also remember assisted upswinging doors carry a weight penalty and they are prone to malfunction.

Maybe a sliding door? So you can open it with part of the roof when another car parked close to you at the mall? (Remember these are wide cars)
But it would have to be a futuristic design. Nobody would like minivan doors on his supercar.