There seems to be no end to the growing list of new and improved things in our lives. I am not trying to dis anyone or technology, it is in my opinion just a fact of life that today the rate of change in all facets of our lives, is faster than ever before.
We bought our first GPS in 2011 when we took off on a trip that took 10 weeks and included some 37 states and seven provinces. Some miscreant needed a fix and we ended up buying our second and then one day, the DW said she knew where we were going(she is usually very good about finding the stores she wants to shop)and about 90 minutes later we found it about 25 minutes from the house. Not where she thought it should be at all. The result of that trip is a reconditioned unit from Garmin with a 6" screen and LTM, that stays in her SUV at all times(except when we're in the RV).
In my "never to be humble opinion", they are the greatest augmentation to paper maps there is for travel. I should say, after past experience.
When we plan a trip to where ever, we take one of the 50 or so AAA paper maps we have available and make our destination with one of those little arrows that realtors like to use to show you where to sign and the use them to mark POIs along the way from home to our turn around point.
We program in out first stop in both GPSs, her 6" my 5" using different parameters and off we go. At dinner we update for the next day. On our first trip with the GPS, the DW started relying on it and didn't review her POIs on the paper map and we missed Monticello.
Reviewing the next days travel on the paper map at dinner and then programming the GPSs allows us to be flexible and include POIs we learn about on the way. Paper map for planning and GPS for execution.
So my recommendation, just buy what you are comfortable programming and watching and listening to. All of ours are Garmin's, neither of the two we have now are RV types. From what I have read, I feel Garmin are the simplest and easy to operate, so that is what I bought and we really like them.
Like I said, it is just "My Never to be Humble Opinion".