I say Arts. For the reasons below:
1. Your chart is left hemisphere focused. You are meant to be pioneer and less of an establishment type. Arts have many many different components, and some are relatively practical. As long as you are making an impact to your environment with freedom you are happy. Arts have less stringent rules and more freedom. You are not a follower.
2. Venus trines Midheaven, also supported by Neptune. This is an obvious one. I've noticed later in life, the profession people fall into or stay in, are related to their nature luck and talent potential corresponding to the MC. This is where you are naturally lucky, why not capitalize on it?
3. Mars may be in 9th, but its the creative sign of Leo. This just means your energies are and should be focused internationally, or in 9th house matters.
4. You are a Pisces. Modern medicine is no longer about helping people, its about drugging people. I would recommend it for a Virgo, but not an intuitive sign like Pisces. Unless you get into a sector like surgery, emergency help as advocated above (red cross like that allows you to travel), or sub-divisions like natural health and energy medicine, you will not feel fulfilled with rigid traditional medicine that traps you with huge loans that takes decades to pay off. (Unless you are rich then the loans will not be a factor.) Talk to people who actually went to med-school and see what they think decades later before you commit. I have friends who went in with early dreams of being a neuro-surgeon and now regrets it, but its too late to change later in life because they are trapped by $250K+ in debt.
Piscean and Sag idealism is shown heavily in your chart. Saturn is also a little weak. To me, this means you need to do a ton of research, talk to real-life professionals and ask the right questions (what is med school really like? how much sleep do you get while in and when you get out? etc.), not what's advertised as a dream, but see reality for what it is, and weigh consequences down the line.
Honestly though, why not do both? Find an aspect of medicine you are interested in and also develop your artistic talent. Nowadays career changes happen all the time and there is no security in one sector anymore.