Hello pankaj,

Every courses of polytechnic is best on their own way. It depends upon your Interest. There are some best polytechnic courses such as

Diploma in mechanical engineering,

Diploma in I.T Engineering,

Diploma in Electrical engineering,

Diploma in civil Engineering, etc.

I would recommend you go for electrical or I.T engineering. Because it has lots of opportunities in government as well as private sectors.

Best wishes!