Depends on whether you want the "video" look or the "film" look. 30P is mostly filmlike, it's not quite as filmlike as 24P but it's much more filmlike than 60i is.
Keep in mind that when shooting 30P you'll basically be ruling out the ability to make a PAL version, so if international sales/distribution is a factor, you'd be better off using 24P or 60i.
