James is my absolute favourite, followed by Harry. For Harry, I'd have to go with the traditional Henry on the birth cert because I don't like diminutives as standalone names.
Jack is nice enough but I'm old enough to see it as a diminutive of John, even though I know it's a name in its own right these days.
Jacob is OK, but it doesn't really please me. I like Jake a lot, but would want Jacob on the bc as it's a diminutive... but I don't get excited about Jacob so I'd probably rule it out altogether.