I'll go with a darkhorse here and say the Rangers.
Sounds nuts, but here's the deal:
1. The Rangers will get another starter before the trade deadline is up and they know that a top flight starter like RJ would most likely seal the division up for them. Not to mention his impact in the playoffs.
2. Contrary to popular belief, the Rangers are not hard strapped for cash plus they just sold the naming rights to the Ballpark in Arlington so there is more than enough availiable cash to sign a big name like RJ to an extension.
3. RJ wants to win and is fed up with zero run support. Run support is definitely not a problem in Texas. With all the Angels talk, he is well aware that if he joins the Angels, they will have to catch the Rangers (currently 5 games back), so why not just join the Rangers instead?
4. There's always a trade every year that comes out of the blue that hardly anyone heard so much as a rumor about prior to it happening, so this could very well be the big one this year.
Now all of that makes way too much sense for it to actually happen, but if by some chance it does, you heard it here first.

Yes doctor, I am sick.
Sick of those who are spineless.
Sick of those who feel self-entitled.
Sick of those who are hypocrites.
Yes doctor, an army is forming.
Yes doctor, there will be a war.
Yes doctor, there will be blood.....