I suspect there are as many OR MORE people living fulltime in "rv parks" than there are traveling. We see permanent and semi-permanent in almost every park we visit. Many are simply living in whatever trailer they found at the time they needed it. In parks that were created with that in mind, many have what is called a "park model" trailer that is more designed to be kept in one place than it is for traveling.
Which trailer would be best depends on many variables .. climate, and what might be required by the RV park would be primary factors.