UG, followed by Sherdog and I have no clue whose number three, it might be this site but I couldn't tell you, maybe it's the UFC.com forums.
You'd think this would be the biggest since MMA Forum is probably more googled than Sherdog or The Underground.
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THE DRAGON RIDES AGAIN - 12/20/14
Machida - Alves - Cruz - JDS - Weidman - Condit - Pettis - Edgar - Cowboy - Dodson - Okami