Shirt collars aren't as much of a consideration with bowties as with neckties since they're mostly covered up by the bowtie. I would stay away from collars that would protrude far below the bowtie, and I don't like button down collars with bowties, feels too restrictive.
Hiding a wing tip or spread collar behind a bowtie sort of seems to defeat the purpose of the collar, too.
So in short, I would vote standard collar for bowties.
When it comes to shirt collars, your first question should be what type of collar works best with the shape of your face. Once you determine that you can figure out what neckware options you have.
There are lots of guides online. Here are a couple:
I've seen some pretty heated debates on this topic on other forums.
I would say standard collars are best (point or maybe a mild spread) but I think button down collars are fine as well. I would also agree that the bow tie is pretty forgiving though so it's not a bad idea to start with a collar that fits your face shape.
I actually like the look of the spread that hides behind the bow a bit, but not completely. I agree with avsmusic1, a point or mild spread looks good, but also that I'd go with a collar style that you like and that fits your face.