I really don't see how Jaime is capable of having a battle with any half-decent warrior at this point, Obara would carve him up in seconds. I still think his path is bound to point back towards Brienne anyway. Trant is a possibility for sure, although I think they will leave him around King's Landing as a familiar face for the Kingsguard.
My money is on Loras. Cersei will try to get rid of him, just as in the books, but just send him South rather than off to Dragonstone. Since he is not pleased to be betrothed to her in the first place, I would think that he would want to get out of there, not to mention the Tyrells and Martells dislike each other to begin with (although they haven't played that angle up too much on the show). Also, Lora/Obara would be the best battle of the options that I can think of.