Jail RP isn't good unless you make the criminal weapons hard to get, not an unlimited stash of rockets in the toilet.
Family RPs are only fun if you go in, make an awesome looking house, and watch everyone beg to live in it.
Space RPs are good on non slate maps like the Build a Space Station map or Planets.
Army RPs can get boring easily without occasional terrorist attacks or out of base missions.
Island RPs are pretty cool if you use a good map or a good built/evented island.
RPs usually based off movies or directly off another game tend to suck.
Medieval RP(G)s are just click click click, and are dumb unless the build is really good and has tons of cool stuff hidden in it.
Camping RP is good in dark maps, but spam comes quite often if you used a map such as slopes dark, and most people tend to make giant huts instead of tents.