Ross' deck with Regigas and maybe Terrakion is certainly nothing to mess with, I expect it to win at least one or two states, I think most of the wins however will go to CMT. This is my tier list:
Tier 1:
CMT
Thunderdome
Zekrom/Eelektrick
Ross' w/Regigias
Tier 2:
CaKE
6 Corners
Reshiboar
Durant
Tier 3:
Mewtwo/Gardevoir
Mew prime decks
Everything else (unless I forgot something).
I'm surprised to see CaKE either forgoten on lists, or just being put really low, but it has good matchups against a lot of the top decks, especially if it runs Terrakion, which can give magnezone a lot of trouble. It also got Prism energy from Next Destinies making it much easier to power up all of the basics in the deck. I Also put Mewtwo/Gardevoir in Tier 3, which a lot of people might not agree with. Mewtwo/Gardevoir is too slow to keep up with other mewtwo decks, so it will usually lose in a Mewtwo mirror match, and it relies only on mewtwo, meaning decks like CaKE, Durant, Mew decks, and even 6 corners can easily shut it down. Gardevoir can also be catchered up easily and KO'd so imo, Mewtwo Gardevoir isn't a good deck right now. Also, I think Reshiboar is the play over Tyram right now, just because you don't put damage on reshiram, which helps against Mewtwo, especially since you will you usually have only 1 energy attached to your Reshiram, it makes it hard for mewtwo to KO you. However, it is still Tier 2 because other decks can set up faster and dismantle it's set up, and it can just run out of steam and lose.
Personally, my deck of choice for states is CaKE/Terrakion.