If you dislike all of the choices, then why do you want a brokered convention? One of these four dudes is going to be picked by the delegates if there is one.
Because I'm a hopeless dreamer. If none of the four can get a majority, maybe, just maybe, the convention will pick a compromise choice that everyone can live with.
While I'm dreaming, wouldn't Gen. McChrystal be an interesting choice? I have no idea if he's even a Republican, but it would be a real slap to Obama. Middle America would love it.