Shut Up and Dance always makes me think of Genesis's more poppy stuff for some reason. It's a decent song, but has been a bit ruined for me by some people I know overplaying it.
I know it's technically from last year, but since the album it's on was released this year, I'm going to say Uptown Funk will almost definitely be my favorite pop song of 2015. I just don't see another pop song coming along that I like as much as that (though I'm open to being wrong).
Edit: You know what, after listening to it again, Shut Up and Dance is pretty good, especially in the context of current Top 40.