If your main thought is improving the already in game ghosts, I'm not sure Paranormal Stuff will do it for you. It's more of its own separate thing in that regard. I voted for Dream Home cause it's the one I've had more fun with, but I think it really depends.
Basically, I think they're both about on par--they each have some extra gameplay, and their own playable "mini-games" in the form of a new career (home decorator and paranormal investigator) so I would say the main deciding factor would be which of those careers sounds more fun to you, and is more likely something you'd actually spend time playing. Personally, I enjoy the home decorator career more, but then I like decorating in the sims and found the paranormal interactions in the paranormal investigator a little repetitive. On the other hand, if you want to commit to living in a haunted house, that CAN be really fun. Both have some good CAS and build items, depending on your taste of course. But neither of them are going to hugely impact your wider game, since they really only contain content that's there if you make an active effort to involve the sim your playing in that content. So, it really comes down to which one has content you're more likely to WANT to seek out and have fun playing. If decorating in sims is something you generally enjoy, and the challenge of working within random parameters appeal to you, Home Decorator is the clear choice. BUT if that's not so much your thing and instead you're more interested in playing through a haunted house scenario or role playing as a paranormal investigator, then obviously Paranormal is gonna be more your speed. Just comes down to what you're likely to actually DO in game, and what kind of game play is more likely to hold your attention.