You just have to get out there and start looking at them... You won't know anything until you can physically see and touch them. NADA is worthless IMO..
Since you are looking used, even the best quality built model, (if any actually exist) can be a POS if it was not maintained well be the prior owner.
Go to RV shows and just walk thru them and find what things you like and what things you don't like and go from there..
They will be all the new/newest models, but will show you what's out there now.
You can poke and prod as you want, ask questions, but they are dealers and will basically tell you anything you want to hear...
When I first started looking for an RV back in 2002, we looked at used rigs.. Only looked at about a dozen of them from every make and they all were just trashed.. Not sure why the dealers put them on their lots to be honest..
After that, only looked for new.. Sure, they cost more, but it would be ours and not someone else's trash.
We bought a new Prowler Lynx made by Fleetwood RV.. They don't make TT's anymore, but that rig carried us to a lot of good times over the next 16 years!! And never let us down.. Sure, basic maintenance and a couple of minor initial things that I took care of myself.
Traded that rig for our current trailer a 2019 Rockwood made by Forest River.
Got one hell of a deal on the trade.. ($6500 and it was still in great shape)
I probably could have gotten a little more selling myself, but I hate doing that.. I just had to sign the title and they applied the trade amount to the new trailer and all was good!
Anyway, just saying you may get a lemon or you may get a diamond.. No one can say one way or the other and for every bad experience with a particular make or model, there are probably 2 times as many that love them...
Good luck and make it fun! Mitch
2013 F150 XLT 4x4 SuperCab Max Tow Egoboost 3.73 gears #7700 GVWR #1920 payload. 2019 Rockwood Mini Lite 2511S.