This is really just personal preference and style. Pinky rings take a lot of abuse-do you want to wear it everyday? Do you want to be able to wear it while adding another ring(s) on a different finger? How do you feel about wearing rings on adjacent fingers?. Some people, myself included, do not like that feeling. Is your jewelry style more demure or bold/eclectic?
If it were mine, I would wear it on my index finger.
What a pretty ring! I have a thing for bow rings, and yours is beautiful!
Honestly I like how the ring looks on all of your fingers -- if I had to rank, I do like it on your middle finger best, and then the pinkie ... I agree with @RMOO that pinkie rings end up taking a lot of abuse so do take that into consideration.