I like Covenant but it is too small to build anything and relies on water pumps.
I like slog as you can put 6 industrial water purifiers in the pool, has lots of crops, and ghouls are the cats meow. But is is far too remote.
Nordhagen Beach is nice, especially as a water farm, but that cabin placement just bothers me.
Starlight is pretty nice, shame that you can only fit 2 purifiers in the rad pool.
The Castle is great once you fix the walls, but unfortunately I seem to hit the size limit too quickly when building there.
Sanctuary is far too large and spaced out, with too many existing buildings to make him feel like my own.