I don't know of any way to determine the relative rates of reactions other than pretty much just guessing. Even with guessing, I can't decide between the last two. Both occur in solution and (if I recall correctly) both occur quite rapidly. I would guess that the last one, just a simple precipitation, would probably be the fastest.
(NOTE: You have the wrong equation on the last one. It should be Ag+(aq) + I-(aq) --> AgI(s) There is no subscript on the iodide ion in AgI.)
