Some features to look for that I was excited to find in my rig under 40g
16 inch wheels and tires e rated
15500 btu ac
50 amp power pre wired for 2nd air
Dual pane windows with deep tint
Auto levellers
8 cubic ft fridge
80 amp battery charger with charge wizard
A floor plan with no "gotchas" like moving recliners to put slides in
External propane quick connect
Battery disconnect
Easy winterize and accessible low point drain
Easy access to sewer pulls (not under slides)
Toilet access with slides in for travel
Hi gloss gel coat
Built in vacum
Not all of these features will matter to all buyers (ie dry campers likely don't care about the vacum) but for me it was a boatload of features that I will use. YMMV
