Trailers are like most things, you get what you pay for. That being said, many things are close to constants. Appliances, equipment such as converters, ac units, and furnaces tend to be the same across brands.
Look toward quality of materials in how its put together. In cabinets, particle board covered in shelf paper is the cheapest, and will show wear the soonest, plywood is better, real wood frames better still. Same goes for drawers and interior furnishings. Built in booth's and couches will follow the same build methods and materials, and generally are cheaper than stand alone units. Exteriors, most folks like the filon or solid fiberglass sided units better, but tin is cheaper, so both have market.
Frames, most use Lippert, a few (ORV was mentioned) build their own, but again will generally cost more.
Warranty and support can also be called an indicator. A company that gives longer coverage is likely to have a little better build quality, likewise a line that warranties "full time" usage can indicate a better product.
Many only warranty their product for one year, and put in exclusions for full time use. Some offer two and even three year coverages with no full time exclusions.
RV companies build many different lines under the same manufacturer, Keystone builds about 10 different 5th wheel lines alone.
Best option is likely to work on finding a size and floorplan that you believe will work, then start looking at lines that build that plan, then narrow to which ones have the quality and amenity levels you want at or near your price point. And discount the unit by 25-35% from stated MSRP.
As a generality mid price units such as you are looking at better grades with better customer support are probably,,,(order may vary by who you ask)
Outdoors RV, Arctic Fox, Grand Design, KZ, Winnebago, Jayco, Highland Ridge, Some Keystones, as well as some lines from FR and the others.
