I think it's all up to personal preference. I went with 19's without lowering and couldn't be happier.
I still may pop some springs on it at some point, but the jury is still out on whether it's a good idea with Calgary winters.
The overall diameter is roughly the same as stock 16" (about 2.1% bigger) so there is still almost the same amount of wheel well gap but visually, granted, the larger rim and thinner tire makes the gap a bit more noticeable. Nothing I think about every day however.
I hear what
is saying and, as suggested, I think the main difference can be in the wheel style as well.
Going darker to blend a little bit with the tire and wheel well, for me, was the way to go.
I agree that a bright colour like white will make only the rims stand out and, by contrast, exaggerate the tire and gap making it look a little odd without lowering.
All in all, if you are all about tweaking the most out of the car performance-wise, you might want to take Preppie's advice and research more.
But if you're out for just something that looks and feels nice in YOUR own opinion, sky's the limit
Fore reference, here is my setup: