I say King of the Cage, most of their TUF guys came from their anyway,
I say leave KOTC where it is and continue signing top talent while featuring the less experienced newcomers on Fight Night cards and stacking the PPV's.
If any it should be Strikeforce IMO.
King of the Cage hasn't been competetion. I don't even order their PPV's.
Strikeforce is a good choice as well.
They only need one domestic, and one internationally. If they can define the opposition as an entity they own, it will cost many many 10s of millions of dollars for anyone else to cut into the dance.