It doesn't matter. You are free to choose anyone you like. Whether it is Sociology or anthropology, you can choose anything.

But as you have asked that which will be more beneficial then i would suggest you to go for Anthropology. I am saying this because i have seen various example out there that how Mains optional Paper can be a King maker or a destroyer.

In anthropology questions are sometimes repeated, there is no new concept coming day by day, you will have to just mug up everything.

All the best!!!