Since you are looking for reviews by motorhome owners, you will probably only find glowingly favorable reviews. I know that the motorhome that we have been living in for the last nine years is the perfect coach, as was the one we lived in before that. <g>
The Consumer RV Group
is a for-profit operation that rates RVs based on manufacturers' specifications and consumer surveys, but I suspect that the consumer surveys play a very minor role in their ratings. Take a look at their site for an explanation of how they arrive at their ratings, then decide whether it is worth paying for them. I thought it was when we were shopping for a fiver when we started full-timing.
If we were in the market for another diesel pusher we would start with Winnebago and Newmar, largely because they survived the big shakeout that occurred a few years back. I would like to believe that my coach manufacturer will be around in the future.
Personally, I would avoid a coach with an Aqua-Hot heating system, although I am in the minority there. The system is expensive, produces diesel exhaust smell, and prone to very expensive failures.
We really like the air leveling in our rig. It is also important to us to have the bedroom, bathroom, and living/dining room separate from each other, since we usually get up at different times.
I don't think that the running gear is likely to be a differentiator between manufacturers of diesel pushers. They all seem to use Cummins or Cat engines, with Allison transmissions. An engine that requires ULSD fuel can be a problem if you travel to Mexico, and one that requires DEF is something of a nuisance since the DEF filling port on motorhomes is on the wrong side at truck stops.
There are various chassis used, and the owners of each will tell you that theirs is far superior to the competitions'. I know ours is, but it's not made any more. <g>
One thing to watch for with a used coach is the age of the tires. A new set can run $3,000-$5,000.
Some people believe that you need a pure sine wave inverter, but we have been living with modified sine wave inverters for 11 years now. We have run every piece of electronics, kitchen appliance, etc. from our MSW inverters with no problem. I have read than some residential fridges require a PWS inverter, so that's a concern if you buy a coach with a RV fridge and a MSW inverter and later want to switch to a residential fridge.
Good luck on your search. It's a buyer's market out there right now, so you can get a real deal on a high quality coach.