Nursing is easily the most in demand job of the choices you gave. Hell, it's probably one of the most in demand jobs i can think of overall. With an RN license you can have hospitals eating out of your palm. If you don't go as far as an RN, you can be a CNA (lowest) or an LVN (mid-level) and still have very high job security. Or you could lean towards the physical therapy market as well.
With an RN license, a 6-figure income is a very good possibility, and with enough experience, could be gaurunteed.
If you are really good at what you do, you could opt to be a Surgical RN, one of the most demanding and tough RN jobs I know. You would side by side with the surgeon during surgery, and if he's swamped, or if he trusts you, he could ask you to close up the patient.
Don't know much about architecture, except that you live life from one project to another, and you could easily go through periods of no work.
I would pick nursing, and not settle for anything short of being an RN.