While I never really did the boat life thing much, I did own a 28 ft cruising sailboat, when I was working full time so did not get as much use as I would like. Though perhaps I did get enough to understand the basic differences between a boat and a motohome, I am semi-retired now, bought my first class A coach in 2016, it is a small class A at only 28 ft (29'5" bumper to bumper), I travel part time, about 75 days per year, though this year is getting off to a slow start.
Now that I have that out of the way, there are a lot of differences between boats and RV's most notably you don't have to worry about RV's sinking as much, though you do still have to worry about them while unattended as wood rot due to water penetration is one of the primary killers of all types of RV's, this can happen on new and old alike, all it takes is some damaged or missing sealant around a roof vent, window or slide seal for water to get in and rot to spread. Last year I saw a less than 16 month old camping trailer with enough roof rot to likely be beyond economical repair, though due in part to the vinyl headliner inside this rot was almost impossible to detect from inside with the naked eye.
As to the question about good brands, bad, brands, etc. this is a very hard question to answer, particularly without knowing if you are shopping for a new or used coach. A lot of RV manufacturers went out of business or were sold in the first decade of the 2000, both around 2000-2002 and again with the economic meltdown of 2008-2010, therfore some once well respected brands continued to exist in name only over the years. Other brands have moved both up and down market over the years, and yet others offer a broad product line ranging from entry level on up to moderately high end coaches. In addition to this if looking at coaches over 10 or so years old, one has to also consider maintainability, as well as known design faults. Take for example Alfa Seeya, which went out of business over a decade ago mostly due to defective fiberglass walls due to a quality control issue with their fiberglass supplier. Or consider no longer available rubber elastomeric suspension components used on some class A motorhomes like many of the Safari products from the late 1990's, turning otherwise potentially nice older coaches into big paperweights due to unobtainable key replacement components, worse yet components that tend to fail due to age alone.
Out of what is left out there in production today, quality control is truly awful with most of them, ranging up to moderately bad at most of the upper end, until you start getting into the million dollar coach market, where some degree of quality control seems to still exist.
