When it comes to gasoline motor homes they are all pretty much built on one or two chassis. Either and F-53 Ford or a Workhorse which has the GM engine. Now where you will find a difference in what you pay is in the house part. You have entry level and then you have others that have better quality cabinets, table and counter tops, ceramic floors washers and dryers. The more glitz, the more they cost.
Some folks like a plain box with no glitz what so ever. No luxury at all, and they are happy with that. Others like luxury and with that comes the things that cost more money bringing the prices up.
So it is up to the individual what he likes.
Now if you are buying new there are companies that have good and bad reputations with customer service. Does not necessarily mean that they are better coaches if their customer service is great, but it does help if you have problems.
The way I look at it IF a coach is built right, it should not need to be shopped for repairs. But some companies have bad reputations for not even answering the phone when you do call them for information about a problem.
You have to do some research and check which brands have had major structural defects and stay away from them. Coaches that are not making the headlines are usually the better coaches. Coaches that might get more publicity on forums does not mean they are better. Most owners are biased towards what they have, so I take their word as not worthy.
Research in different forums. If you are interested on a certain brand, go to their forum and see what owners have to say. There are forums for just about every brand manufactured.
Then there are the one's that say buy a Prevost or Newell even though they are driving an entry level gasoline motor home twenty years old. Don't know why they do that when the OP was asking which was a good gasoline coach.