Unless it’s manga, I don’t really pay attention to the art style of each individual work, so I guess I could talk about the animation studios’ styles? Yeah, that works.
You gotta love Shaft‘s 90+ degrees head tilts, though.
But more seriously, their use of bright colour and endlessly empty scenes, save for the necessary characters and items, don’t allow you to focus on anything other than what they want you to. It also creates a nice atmosphere I’m quite sure how to explain…This style is most prevalent in the Monogatari series, although it also comes through in some of their other works, particularly Nisekoi and Mekakucity Actors.