Well, basically, The World God Only Knows tells the story of a guy who's like the god of dating sim games. A couple of things happen, and, well, he ends up having to use his dating sim abilities in real life and conquer the heart of girls. It's actually pretty interesting.
Anyway, what follows are serious spoilers, so you've been warned. At the end of the story, there are many routes the protagonist could take. He could opt for the harem end, choosing some of the girls he had conquered, which would be fine. He could also choose to settle with just one of the girls he had conquered; there were many top-tier heroines in the series; one of my favorite ones was Aqua, who actually wasn't a romance target. He could also opt for some of the mid-grade heroines. There were tons of those. Not too bad, but not too good either. However. HOWEVER. Despite having so many amazing options, he went with the worst heroine in my opinion.
Seriously, there were so many girls, and yet he had to choose the most boring, most bland, most plain one (again, all of this is solely my opinion). I was already pissed that it didn't go for a harem end; there was already a supernatural element in the story, so realism be damned, harem end could work; if a supernatural/fantasy story starts as a harem, at least to me, it should end as a harem. But no harem. That's fine. I can live with that. Surely that means he'll at least choose one of the best girls, right? And... well, I already told you how it turned out.
Anyway, yeah, that's certainly not the kind of ending I want this story to have, like I already mentioned. I believe there were some people who liked the ending of TWGOK, but, if I remember correctly, they were the minority. For a very good reason. The girl the protagonist chose was nowhere close to being best girl.