I'd say OneFC over Bellator.
Gonna have to pay him a few hundred K or more depending on if OneFC is offering him a big deal. Do you do that and throw him to the WW wolves where he'll get wrecked? Or do you spend that much money and develop him as a prospect fighting the lower level WW in your org? Thats alot of money to spend on someone who fights the Ottow's of the world.
Thats why UFC let him go. They signed him, pushed him, paid him and thought he was hte next phenom and then he showed he wasnt and they walked it back. He fought low level guys on fight nights with little hype behind it. They werent gonna overpay for him to continue doing that for a few years unless you thought he was champ potential or a superstar you couldnt let go.
One has money to burn, he can beat basically everyone over there probably.