Someone made a good point in my FS today, and that is with the new way that troops will be generated (un-linking the three military buildings and having a separate queue for each), that a Brown Bear may not be as useful in particular to people further along who have all three fairly highly upgraded.
This will require a wait and see aspect for me, but I may be using so many supplies to run those three buildings that feeding the Brown Bear happens less and less. I still love the free troops from that building, though.
I would hazard a guess that for early game, especially if you don't have a Phoenix to feed all the time, the Brown Bear will still be the best choice. For late game, I think the Moon Bear is pretty attractive with all the KP I can get (the Chapter 16 KP requirements are my current limiting factor).