RV's are "rated" in a number of different categories. Price, weight, features, length, tank sizes, sleeping arrangements are just a few that come to mind.
You can go to the Keystone website:
https://www.keystonerv.com/brands/ and scroll down to fifth wheels. You'll find a photo of each Keystone brand with the following info:
Starting MSRP
Starting Length
Starting Weight
By doing a little math, you can calculate "cost per foot" and "cost per pound". Those two bits of information, although not "all inclusive" will give you a good indication of how much each trailer costs, in a measureable unit. That should give you a "lineup of trailers produced by Keystone based on cost per foot and cost per pound. If you arrange them in order from "cheapest per foot and cheaptest per pound" you should have a list of brands produced by Keystone arranged from "entry level" to "luxury level"...
That list will give you a good idea of just where each Keystone brand lines up in two categories, Find the trailer in the "price range you want" and then start looking for a floorplan that fits your needs. You'll need to "hand massage" selections based on moving up and down the "brand hierarchy", but the above lists should keep you somewhere around the "quality/price" grouping your budget allows.
There's no need to only look at Montana fifth wheels (very expensive and very heavy) if your budget or your tow vehicle can only afford a low priced ultra-lite model. The same holds true for looking at Springdale fifth wheels if you need a toyhauler with sleeping accommodations for 10.