Airbags explode & pop. but they are very comforting to ride on. Hydraulics on the other hand are very high maintenence think of a chevy impala hoppin'. Air cylinders are reliable. I'd go with cylinders if you want to get up those bumps easier. Most people don't want hydraulics beacause the celica already performs best suspension wise. Hydraulics are good if you do plan on going up the speed bumps and dips but an excellent setup is costly. I'd get hydraulics but then you think about performance.
Some celica peeps love the way their their suspension already handles and they just want to spruce it up a bit with little odds and ends. Think of it like this you have a turbocharged that's capable of doing 13's or 14's 1/4 mile. then say you add hydraulics what's the point? For the most part if you like draggin you car of havin' a little fun hydraulics wouldn't be the investment for the suspension.
Preference again i'd get air cylinders to go over those nasty bumps and it is fun to watch i have to say also will get you major points if you do car shows of some sort. Then you got your daily driving routine I don't think it's practical but if you like hydraulics and just to cruise that's cool. I'd go with air cylinders again a very high maintenence project and not many people have done it. It's a project but it can be done. I'd have to say though I love seeing cars that lay low to the ground side - side, front back, 3 wheel, pancake, smack dumped it's fun to watch if you do it that'd be very