 If you liked Kami nomi zo Shiru Sekai |  ...then you might like Monogatari Series: Second Season |
Both series have Multiple Heroines, but Kami nomi is a little more open in the romance aspect. Comedy is a strong point in both series, and there are sci fi elements and lots of stories in kami nomi.The plot gets more and more rich and interesting as the seasons advance, in my opinion is a great option if you are looking for something similar to Monogatari.