Dear Rajnish
Basically core branch means which we are going to learn in depth of that branch like in Mechanical we're learning about machines, in Cs learning about computers, coding etcc.,
These are the best engineering branches:
Computer Science & Engineering/IT
Electronics & Communication Engineering
Electrical Engineering
Mechanical Engineering
Civil Engineering
Environment Engineering
Chemical Engineering
Biotechnology
Genetic Engineering
Aeronautical Engineering
Take wise decision, while choosing.
All the best