I did bio, chem and lit, and was accepted for medicine.
Supposedly, an understanding of humanities, not to mention the essay writing and critical thinking skills the field encourages, has the potential to create more empathic doctors (a key theme at present in medical admissions).
Primarily, I would do what you enjoy, what provides confidence, and what you feel you can achieve most in. As long as you believe you can score well on pre-admissions tests, I would favour the humanities route.