All factors considered, circular ramps are the best option. Here's the Riverbend Garage in San Antonio. I've parked in this garage many times, including in my father's 1983 Oldsmobile Delta 88 sedan (a big car). Yes, the ramps taking up some space, but they leave the rest of the garage with flat floors. Also, you can park on the 8th floor and exit the garage in about 90 seconds as long as there's no traffic in front of you. In a sloped garage where you have to drive through every floor to get to and from the top, it would take you much longer even with no traffic. With the curved ramps, even in rush hour, the people on top can enter the ramp and be on their way instead of having to be last in line because of the people on the lower floors.
https://www.google.com/maps/place/Ri...1!4d-98.488532