Difficult to say. The staff balances the game so there is no one supreme Clan.
Mono La Junta is good because of Support. If you can afford these cards, consider this deck:
Arnie, Bryan, Ethane, Floyd, Isatis, Milena, Natasha and Trish.
If possible, get Glover, Walker or Pilzken. They are top tier choices and Emeth Cr is one of the best La Junta collector cards.
Use Freaks against Life increase and damage reducers
Use Raptors against Attack manipulators
Use Vortex and Riots for Pillz strategies
Use Huracan to combine Life increase with heavy Attack manipulation
Use Pussycats to reduce damage
Use Solomon with high star cards and draws
Use Mr Big Duke to bypass the conventional Damage reducers...
No one supreme strategy. Every deck can help win or make the game harder for you. It is about matching strategy with playing style.