In reality, though, unless both company's vans pulled up simultaneously at LAX, I'd take whichever one comes first. So, it's more likely that a Prime Time Shuttle van will fill up more quickly and be on its way to Anaheim than a super shuttle van and since there are fewer seats, it will make fewer stops to drop off others.

Note: Prime Time Shuttles uses 7 and 9 passenger vans Super Shuttle uses only 9 passenger vans. The seats in the bus are a little more comfortable there is a restroom on the bus (but it has gotten some scary reviews).

If not, you'll either ride around on the bus to other hotels or be transferred to a (ahem) van to be taken to your hotel - either straight away or after others have been dropped off. If you're staying there, the bus might get you there more quickly. Plus, when you arrive in Anaheim, the bus always stops at the Disneyland resort to drop off passengers first. Add to that, the vans are 'on demand' if there are more passengers waiting, they bring out more vans the bus, however is SCHEDULED (one bus every 30 minutes, most of the day). Apart from being less expensive, the vans are much smaller so they don't need that much time to fill up (they don't have to stop at all of the terminals like the bus does) since there are always people ready to fill the van in front of each terminal. If it were me, I'd take the 'shared van' (super shuttle or prime time).

Prime time shuttle disneyland