Lots of strong opinions here.......I love the lively debate.
My two cents.....
The Eagles did have a great ride, mostly because of the very long amount of 'travel' in their suspension, that could absorb the largest potholes with ease, along with independent front suspension.. That said, if the shock absorbers were not maintained or changed when necessary, they could rebound excessively, yielding a ride that could induce 'seasickness' in some. The Eagle's were great handling curvy roads with superior handling characteristics. Very little free play or slack in the wheel. The early models had Ross cam and lever steering, and despite not having power assist, were easy to steer as long as you were moving slightly. Later on they gained power assist. As for 'superior cooling system'....well around here, we used to joke that the Eagle's came with a soda can....you know....to prop open the engine door a few inches to prevent overheating.
And the Eagle's had a twelve volt electrical system, versus the 24 volt system used in the MCI. If you left the florescent interior lights on a bit too long without the engine running, you had better have some booster cables nearby....
As for the Van Hools....our 2006 and 2009 models have a truly harsh ride. Our 2012 and newer have a much improved ride, but still inferior to both Prevost and MCI.
One thing I will say for the Van Hools....in certain aspects they seem much higher quality than our Prevosts...the baggage doors and other exterior doors feel and operate much more substantially than our Prevosts....the fit and finish, the panel gaps are superior. For example, to open the H3-45 lav service door, you must press your foot against the battery door, or the fiberglass edges will bind, preventing the opening. The rear engine door operates very nicely on the Van Hool. The one on the Prevost usually must be slammed hard in order to engage the latches on both sides.
By the way....the air conditioning on the Van Hool is delivered from the overhead vents, that are just ambient air fans on the Prevost and MCI's. The floor ducts on the Van Hool are strictly hot water for heating. the Van Hool has an advantage there, too.....the preheaters not only heat the radiator with the engine off (can be preset on a timer), but actually circulate the water and heat the entire coach. One more Van Hool advantage....the cabin goes all the way back to the rear of the bus, allowing the optional rear window. The MCI and Prevost have exhaust equipment taking up almost the equivalent of a row of seats. So with the same total rows, the seat pitch is better in the Van Hools.
Now to the D4505's....we only have three in our fleet, and I am not too familiar with them, as they normally don't run into The City. They are used on our Albany to Long Island trips, to comply with the State requirement to keep them within New York State. (trips to The City cut thru a corner of New Jersey). Today we had one, (62117) come in on a pooled Greyhound trip. I got to move it from one gate to another in The Port, and did not detect any foul odor from any source.....