I would like to say that the similarities about these anime is the view angle and the slide scene of the anime while the story is going. they bot got fast slide and even get many scene with only a few moves. the different is nekomonogatari got a smoother art style than mekaku. i wouldn't say it better cuz i believe as a mekaku fan, mekakucity actors has its own style. and i probably like it more.
* Both have similar genres and dialogues..[which is really boring]
* Both have to deal with weird wishes/supernatural beings...
* Harem starts from the 1st episode..[I'm talking about all Monogatari's of course]
* Both male MC's are seriously dumb...or dense af...
* both have likeable supporting characters [they're the only one who acts logical btw]
Both animes have to do with a boy falling in love with a "monster" girl.
Both have to do with dangerous "monsters" and myths
Both have the MC looking after the girl
Pretty much the same as far as main couple go except Sankarea has zombies, while this one has demons