Units change. I used to be on a great unit, and then one day I woke up and realized it'd gone completely toxic.
My self-esteem was so poisoned that when I went on one interview, one question was, "Tell me three words that coworkers think of when they think of you," and I was utterly unable to say anything good.
Maybe I should've gotten out sooner. Regardless, that failed interview question was the biggest eye-opener, and I needed it. It was quite a process to evaluate my skills and my options, and if I had to do it all over again, I would probably be smart and go to a few EAP sessions to sort out all those emotions.
That said, my advice is to always keep your options open. Keep your resume up to date, keep your references relevant, and do timely self-evaluations (not how your manager or coworkers see you, but how would an outside employer see you?) and take control of your career. Be proactive, because change is going to happen, and if you find that change to be intolerable for one reason or another, you will be ready to do what you have to do.
Best wishes, whatever you decide.