This is a choice that can vary from individual to individual. It is each student’s unique preference of certain things like location, curriculum, alumni, crowd, etc. that influence their choices.

One of my friends cleared both the entrance exams at the same time but opted for AIIMS over NIMHANS, due to its location. Being a North Indian he felt it would be easier to blend in rather than getting accustomed to a new culture, food or place.

Also, he mentioned that the Neurosurgery course will only provide an McH degree and no MS degree. This was also another concern for him and why he in the end went for AIIMS.

Therefore, you should think clearly and point out all the pros and cons of these institutions. Check which one is satisfying all your requirements and then go for it. Both AIIMS and NIMHANS are reputed institutions, graduating from any of them will prove to be great for your career. If you are North Indian go for AIIMS, if South Indian opt for NIMHANS.