I think that speed is more important for making a roller coaster exiting. although acceleration is also important for that fast, scary feel in general speed is more important. First of all doing corkscrews or going upside down you need to be going fast so that it is safe. This works by using centrifugal force or inertia. If it is too slow you wouldn’t be able to do it of have to need very heavy buckling for safety and, that wouldn’t be fun. Also I think that the main thrill factor in a ride is speed, when you take that away stuff that was fun becomes boring or even unsafe. In my opinion the faster it is the more fun and exciting even if it takes longer to accelerate to that speed. If you look at any scary or fun ride right now it will be fast
