I would recommend Lovestruck because it affects gameplay in whatever world you're in. I own all three, but haven't yet played with horses or residential rentals.
I might have tried playing For Rent if I wasn't scared of the bugs, but so far I haven't played on a lot big enough for horses.
Some caveats, for Lovestruck I have a mod installed that doesn't allow relationship decay by time alone. I also have one that allows me to turn off attraction for individual Sims. You also have to take the time to give Sims turn-ons and turn-offs or their attraction will always be neutral.