Whenever this question has been asked over the years, I've seen Olympia Looping being mentioned the most often. In its high-capacity configuration it runs "several" trains (Wikipedia does not cite a number) carrying 28 people each. With a ride time of 1:45 - let's make that two minutes, for simplicity's sake - it translates into a capacity of 840 people per hour per train. Even with three trains running, it would mean a capacity well above 2000 pph.
Expedition Everest is also quite the crowd-eater. Dual loading platform, five trains, 36 riders per train, and a ride duration of 2:50. If we approximate that figure to say that five trains are dispatched in the time it takes the first train to complete the circuit, it means 180 riders are dispatched in three minutes. That gives a max capacity of 3600 pph, which admittedly is wildly optimistic. Wikipedia pegs it at 2050 pph, which still is pretty darn good.