Welcome and best of luck finding the perfect egg for your retirement adventure.
I second what Tim said attending a rally
is far and away the best and most fun way to shop for a FGRV. The second post "2014 Rally Map on Google Maps" may help you find something to attend. Rallies, Get-togethers, Molded Meets (Upcoming) - Fiberglass RV
Grab your tent and head to one or spend a night in a motel, Saturday tends to be the prime day for open house type activities.
Different manufacturers put more focus and emphasis on producing campers aimed at different parts of the camper market. Much the same as Ford, Mercury, and Lincoln while having much in common focus on meeting the needs and desires of different market segments, at different price points.
Just as you can order a Ford with options that add value and price to move it into the Mercury or even Lincoln price point OR purchase the up market brand with value added options already included you can do the same with trailers.
I won't attempt to put the trailer manufacturers in some sort of order but Scamp
tends to have some less expensive utilitarian offerings with "deluxe" packages or options that move the cost/features up to those of the up market brands "standard" packages. They have been making much the same campers for decades.
tends to be a bit more up market and has put some effort into designing to meet the needs and desires of the retiring and empty nest baby boomer market. They offer some larger models with more amenities as standard that are geared toward this market. As have some of the other newer manufactures of FGRV's.
The 15 to 17 foot models offer a nice balance of more room and a easy to tow package.
What you need for a vehicle to tow with depends on the camper, if you just wanted to sort of scope out vehicles I would shoot for something with about a 3,500 lb. tow capacity as a general guideline.
I think you are being smart, you have time to narrow down your choices in campers, possibly pick up a good late model used one if opportunity comes up and shop for a good deal on a vehicle that will match up with your narrowed down list of campers.