From what I've seen/heard, those two companies have the best management systems. I've never seen RideTech in person, but I've heard they make high quality stuff and I think even Gas Monkey Garage uses it on all their builds.
I've seen AccuAir in person, and it's legit. They always make high quality components and introduce new ideas before anyone else (that I've seen).
You can't go wrong with either. They're both going to be a pretty penny. If it were me, I would go with AccuAir because I've seen it in person, I like the idea of their new[ish] height sensors, and it's generally cheaper than RideTech.