Between PKI and Worlds of Fun, PKI. They have a much better collection of coasters. If you like fast wood, PKI is great, Beast and SOB, plus the Racer. The giant loop on SOB is a coaster moment you should experience. SOB is not about airtime though, its about fast high banked curves. Same for Beast, its about speed. Also, if you want to be inverted without shoulder harnesses PKI is the place, SOB and Flight of Fear.
The Flight of Fear is another excellent coaster. If you go there, hit it first as lines build up and waiting inside the building gets tiresome. There are 2 trains with only 20 seats each, and loading time is a little longer on this ride, thus the slow moving lines. Its a great launch ride.
The Vortex is an arrow mega looper that runs pretty smoothly for its size. The mine train there rides rough for its size though, but it a nice little ride. Top Gun is a short but fast suspended coaster.
The other coasters there are skippable, so you have 4 great and 3 good coasters to check out at PKI IMO.
The flat ride selection is a little short there, but they have a swinging ship, flying scooter, slow scrambler, bumper cars, trioka, monster, and a wave swinger. Rapids ride, falls ride and themed log flume for water rides and a haunted theater dark ride. Enough to fill a day.
Its a wonderful park at night, especially International Street and the Eiffel tower in full lighting. Try to take a moment to absorb the atmosphere there after the rides close if you can.
The park itself has become a little cluttered and theming has went to the wayside since Paramount took control, but its still a nice place to go.