Hello aspirant!
Answering your question-
BAMS and Physiothearpy both have good scopes in India but if you want to settle or do job in other countries Physiothearpy is the best as I am myself pursuing my bachelor's degree in PHYSIOTHERAPY. I think physiotherapy is better than BAMS. Both are different fields.
BAMS deals with ayurvedic medicine. Physiotherapist are in great demand in sports field, any health issues like back pain, hip pain, shoulder pain, sciatica, for pregnant ladies, and more.

BAMS Ayurveda prescribe medicine in which their will be chances of addiction of medicines. It takes lots of time to get result in Ayurveda but by giving the physiotherapy treatment there will be immediate result can be saw within 2 or 3 day or more then 2 weeks.

Hope this helps you

All the best for your future.