Party balloon filler at your local supermarket. Nobody breathes more noble air than them. As for a serious answer, I consider the most noble professions to be those people who own companies and, rather than trying to chase short term profits, chase progress of some form.
That's an interesting answer. I like it. I Think that this is somewhat of a silly question. There are any number of professions, and they're only as noble as the people that join them. What I mean is that someone's motivation to be a teacher could be to have a job where they get the summers off, can get tenure and be protected while being mediocre at best. However, someone else could bypass a high earning Job in the private sector because they want/feel they have a calling to teach. The profession is the same, the motivation very different. Therefore, I don't think any particular profession is the "most" noble, but some of the people that occupy those professions may be quite noble, or quite disgusting all within the same industry. TLDR: It's the person, not the industry.