Ryouko/Ma-kun. Not only best girl, but best boy and best relationship. They're the best. Really like Sugawara/Takano and Yuki/Jun too. Dating master is the best character, all scenes that he is in are 300% funnier than the show average.
On the other side, Chiaki and Kana are the worst. They both know that the other wants to kiss and almost fucked, but have no balls to do it, and I'm pretty fucking done with this trope.
Takase and Kanda are similar, but they're a lot better in that they don't understand what the other feels, so misunderstandings are justifiable.
I really hoped we would get their endings in the next episode but it sounds like the manga isn't over yet so I'd rather they revisit it in a season or two to finish it properly.