I have a medical degree. Things are far better than in other fields, I think. I start a residency in may (I might or might not stay since a cold made me do the exam worse than I expected, so my choices are more limited than I expected given my performance at simulations, but it's still a decent score and I hope to still be able to pick hemato at a decent hospital. If that fails I'll likely retake, because the other options I dont personally find that interesting -which is not to say that they are bad. They're just not that relevant to my interests. There are a couple of specs that interest me, and others that dont.). Besides that, there's always the temp jobs as the doctor or a workplace, or shifts at the ER. So yeah, things look decent enough, in general, in the professional sense. Certainly better than for other scientific degrees.
Re: research: biologicals are expected to be in 80% of treatment protocols in a medium term, so maybe excepting primary care specialities, there should be chances to see interesting things in pretty much any field, so go for a speciality that you find interesting in general. That aside, hematology is one of the most cellular biology oriented specialities. And in the hospital of the university where I studied, the dept of Cell Therapy was headed by a hematologist (I suspect that given the nature of the field this is not unlikely to happen elsewhere). But yeah, all paths lead to Rome. Yamanaka and Anthony Atala are two prominent stem cell researchers, and they are respectively an orthopedic surgeon (which is a very nice speciality in which many interesting breakthroughs are taking place) and an urologist. So TL,DR, see what speciality you like best on a day-to-day basis, and work your way to research from there. That's what I intend to do, anyhow.