Baconator7

I personally prefer the Underwater Home because of better features and a better atmosphere (IMO), but both are good. My main beef with the Underground Hideout is that the terminals spread throughout the hideout have a very easily accessible and very tempting cheat function, which can be used to fully stock the kitchen and armory with food, explosives, and ammo, which ruined immersion for me, and that stocking ammo to the shelves seemed to be duplicating it (which I'm positive the Underwater home doesn't), but it really is your own preference because they're more-or-less the same thing with a different layout.