1. UFC
2. Proelite (include eliteXC, strike force)
3. Dream (if they keep it up)
4. Affliction/adrenaline MMA (having signed guys like sylvia, rothwell, lindland.....but could fall easily like M1-Global)
5. IFL......dont know how long they'll last though, dont think much longer.
Really when you think about it, there really isnt much competition for the UFC, Dream is targeting an audince who the UFC doesnt rely on, IFL cant really compete with the UFC, and it looks like it wont hold for much longer, so its comes down to the Proelite promotions, who are a threat based on their recent TV deal, aflliction and Adrenaline are starting Big, but may realize it isnt as easy, and take a fall just like M-1, their best shot is at doing Cross Promotion shows.
Although their is a dark horse whom could take all by surprise and rise to the top, that of course Would be YAMMA pit fighting