I agree with Tau being bottom of that list actually.
They are easily the most bull**** army to play against as all their rules basically remove player interaction and chance, but they have too much difficulty scoring objectives vs the other top tier armies. They are only good for seal clubbing mid-tier codex armies.
Honestly if they didn't basically auto-lose to Eldar with at least 2 Wraithknights(god help the tau if they get invisibility) then I could see them higher. But when the paper to your scissors is the most common army played in tournaments... yeah not good.