Silver would be the easiest to maintain. But I would go for a 13 just for the fact that I think the 14 will be nothing to brag about. Most of the bugs should already be taken care of by now as well, it's not like tehy keep putting bad parts in the 13 and go, "hey the 14 is going into production, let's put the good stuff in." They fix as they build, so I would take a killer deal on a 13
