I heard Aaon was designed by two former Lennox guys.
Sometimes the assembly line forgets to wrap those reheat valves with wet rags and that's why they leak-not because the valves are crap.
We had an L series class in the shop and they brought a trailer in with an RTU to let us look at it and see it run. I was new and I asked "did you guys copy an aaon?" they did not think it was funny.
We see a wide range of Aaon unit types and ages. Their old stuff is good and the new stuff is built like the old stuff. A lot of times when I work on them i find my self asking "why doesn't anyone else do it like this?" those units were old too. Things seem easier to get to, coils seem more robust and most of the time are slanted, hinged doors and latches with hardware to hold it open, slide out blower assembly's, gear drive economisers, etc etc. I am mostly talking about general RTU from small to 50t. Not every Aaon is great like the liebert wannabes we see. I have changed a lot of parts out on RTUs and for the most part they seem a little smoother than most. In our shop the most grumbling I hear is startup issues and bell and whistle overload.
Some of the other manufacturers could take a lesson on their wiring diagrams. One of the easiest diagrams to read IMO.