It's going to be very interesting to see who Miami can get to fill out the roster around their big 3 if Lebron signs. As far as I can tell, at best they could maybe trade Beasley for a centre, keep Chalmers and fill out the bench with vet minimum players! I don't think they even get a MLE to use, since they are under the cap.
Knicks would have trouble finding enough talent to surround Lebron and Amare with this season too. They'd have to try to dump Curry's expiring corpse (I mean contract) on someone to acquire another decent player. Other than that, they have Chandler, Gallinari, Douglas and Walker. Not nearly enough.
I still think Lebron's best chance to step into a team that can contend immediately is Chicago, but for some reason there is zero indication that Lebron is leaning that way.
Miami appear the favourites right now, but I do think there is a good chance that it is just hype from Lebron's camp. I think Lebron craves fame and money more than he wants an NBA championship. Can you imagine Lebron wanting to share the limelight with D-Wade, let alone Bosh? Too much of an alpha dog.
I'm going to say he'll go to the Knicks. It'll take longer to be successful, but the chance for glory is greater. He'd be lauded as a hero if he managed to save the Knicks from irrelevance and bring them a title.