There's no one good answer, because what works for me may not work for you. It depends on where you want to go. If you fly JetBlue, that's a good choice for you. The points don't expire, so that's another good reason to transfer them there.
I don't stay at Hyatt's, but it's a reoccuring theme that UR's have great value at Hyatt. I've never flown Jet Blue because they don't fly where I'm going. I use my UR's mostly on Southwest or United.