For shaman sets:
Classic > BC > Cata > Wrath = MoP
If shaman T16 turns out to be the set shown in the shaman forum (and on the general board) last week, flip MoP with Wrath. To be fair, though, there have been very few shaman tier that have been lackluster. T4 was a bit bland. T14 was terrible, imo (lol peacock).
Now for overall? Oh god my brain hurts trying to think that one out.