Seesh, they ask about RV GPS's and get ONE reply that actually discusses RV specific GPSs
The Rand Mcnally GPS is sold in several different flavors and models. The first (7710) appeared to have lots, and lots, of issues "bricking" (ie dead), crashing, freezing etc. Later models appear to be improved.
The Garmin RV-760 is based on the Dezl-760, with some of the "trucker" stuff removed and some specific RV stuff installed (like campgrounds)
The Tomtom 1605M is their entry, which I am not as familiar with as the other two.
All appear to have various campground info installed. The advantage of their data-bases, over the standard Campground POI from the POI factory is they all have actual information on the campgrounds. My understanding is the Tomtom is weaker here then the other two (KOA campgrounds -may- be all they have).
All three appear to have programmable height (ie overpasses) and length.
All three will lead you "oddly" sometimes.
Personally I've used Garmin for my personal use (and many others for work). That being said, I'm not certain the Garmin RV760 is clearly better then the Rand. I'm worried that the "new" Rands may have the same issues as the "old" ones.
I also don't like Tomtom's user interface.
For that tout Microsoft Streets & Trips (since I've never used it). Will it warn you about low over-head passages (ie overpasses/underpasses)? Will it warn you about roads unsuitable for the length or weight of your rig (ie weight restrictions on bridges)?
All of the RV/Trucker GPS's will do that.