I would advise you to learn Sanskrit, because it is a classical & beautiful language. Hindi, like most other Indian languages, are derived offshoots of Sanskrit - each much easier to follow & speak than Sanskrit.
So, even though learning Sanskrit may sound scary to most people, if learnt from a good teacher, I am sure you would find it much more logical to follow & hence captivating too!
Hindi can be learnt for practical purposes with a little extra effort after learning Sanskrit. But remember, please start learning Hindi only after learning an appreciable amount of Sanskrit whereby you can independently read/write/comprehend the meanings of a few sentences or paragraphs at a time. I suggest you don't mix them up trying to learn them simultaneously, at least in the beginning.
All the very best, TC.
