Which branch of engineering should I opt for in B.Tech after completing the 2nd PUC?

Most people look at core branch like mechanical and electrical, or computer Science, so go for it, because there are good opportunity in different jobs.

First of all, look at the different types of engineering course available in your preferred place, then maybe take career guidance test of engineering which might give you a better idea to select, then understand your likings based on the types or areas of jobs you would be offered.