Any specialty is what you make of it. Pick the specialty that interests you and don't worry about the money, there is plenty of it out there. I used to have an OMFS faculty in dental school that complained about money, there are Orthodontists that complain about how OEC is going to ruin their profession, and there are people that say implants will be the end of Endodontics. There are always going to be people out there that complain about their profession no matter how good it is going. I chose a residency in Periodontics and have absolutely no regrets. Its true that I probably could have specialized in something else but, the fact is, I am happy doing implants, mucogingival surgery, and grafting procedures. As for which school to pick, do a little research of your own on the different programs and find one that is suited to your needs.
Things to look for in a program: clinical vs. research based, clinic time, procedures performed, faculty-to-resident ratio, access to patients, and, something important to me, how well does the program prepare its students for board certification?