Date A Live, Yamada-kun to 7-nin no Majo (TV) Recommendations
So both of these involve a teen boy getting dragged into a fantasy-like world which involves kissing some girls. Yamada has to kiss people for certain reasons that are explained in the anime and then Shido kisses the spirit girls to lock away their spirit powers. So in a way they are quite similar, both are about one boy and a group of girls pretty much with some supporting characters here and there. They are both heavily comedy with some romance. So I think if you enjoyed one you should like the other.
Plot involves Male MC dealing with girls having supernatural powers, and by getting them to kiss, either seals power shut or reveals what power the girl has. Only difference is genre-based on magic vs "other-worldly" / (I wouldn't describe Tohka as an alien?) and Male MC behavior on delinquent vs average Joe.
These two anime are really similar. Both have male leads who can save girls with kisses. In Date A Live, the girls are spirits whereas in Yamada-kun the girls are witches. Both have harem and ecchi components. Date A Live, however, has a lot more actions and fighting. Girls in both anime have their back-story.