When I was at the park last week, Riddlers Revenge had the SLOWEST dispatch times ever. Even with the GOLD Q-Bot, we waited in the station room for at least 20 minutes (While single riders were just walking right on). I remember being on the ride outside the station just standing in the heat for a while before we could get off. As for Goliath, they were running 3 trains for a while, making you have to sit out of the station for a while in the sun as well. In fact, many times I saw both trains sitting outside the station while a 3rd one was still being loaded. The ride kept stopping on the lift hill, and later in the day, they were only running two trains (which actually made the wait seem quicker). And there were many workers in the station then as well. I honestly think X2 and Terminator had the best dispatch times.
As for the Q-Bots, for the most expensive Q-Bot (PLATINUM) Your wait time is hugely reduced and not only is your wait short, but you get to ride it twice in a row. However, It depends on when your going if this is necessary. I have gone durning very busy times of the summer, gotten a GOLD Q-Bot, and gone on every ride multiple times. And yes, X2 is 15$ extra per seat, but I get that each time I go. It is well worth it.