There is no legitimate answers to a question like that. Someone who's been through both could give you their personal opinion but that wouldn't settle anything. As far as the material goes, they're both on the same level but it's not like either one requires any sort of skill. You just spend enough time to cram information into your head and pass exams.
It's the equivalent of MMO's in the gaming world. Not actually skilled? Don't worry, just spend more hours per day than anyone else cares to and you'll come out on top!
If you were truly smart, creative, and had people skills you'd be involved in some entrepreneurial venture doing something you love while helping others or on the leading edge of innovation in whatever industry.
People in the medical field deserve much respect but let's not kid ourselves into thinking it's where the brightest end up. Creativity is a huge part of genius and in medicine there is none. So, unless you're Gregory House I would think twice before thinking of yourself as anything other than a drone just because you're a doctor of some sort.
Now, I don't mean to imply that none of you are anything more than drones. Most of you reading this are much much more. But that would be true regardless of your profession.
I've gone a bit off topic so let's bring this back. The person who usually asks this is wondering if one will be significantly easier than the other and if so, they might as well choose this as their career. To them, I would say that both paths are very difficult and before beginning their journey to make sure to shadow people in the profession to be absolutely sure this is what they want. Once there is little to no hesitation about whether or not you want to become a doctor, pharmacist, orthodontist, optometrist, the rest is relatively simple. Just make sure to stay focused and spend enough time every day to be able to retain all the information. There is nothing difficult about reading what others have discovered and improved upon. There's just a lot of it. All you need to do is read, take notes, use patterns or whatever techniques that help you understand and remember the information.
Spend enough time studying, and after 4-6 years of the grind, you'll find yourself with a degree. Is that hard? I suppose it depends on who you ask. And whatever opinion you receive, I'd say I wouldn't disagree with that.