after engineering which exam is best upsc or gate

Hello aspirant
Firstly you need to understand the definition of both exam and understand that both exams are quite different as well as have different purposes.

UPSC examination is a nationwide competitive examination in India conducted by the Union Public Service Commission for recruitment to various Civil Services of the Government of India, including the Indian Administrative Service, Indian Foreign Service, and Indian Police Service

Where as GATE exam (Graduate Aptitude Test in Engineering) is a computer  test conducted at the national level in India. Qualifying in the GATE exam is a mandatory requirement for the engineering graduates who are seeking admissions to the Postgraduate Programs like Master's and Doctoral with the Ministry of Education (MoE) and other Government Scholarships / Assistantships that are subject to the admission criterias of the institutes.

So you can summarise as that UPSC gets you a govt. job where as GATE gets you a degree.
Personally I would suggest that UPSC is a better examination which brings respect as well as other benifts of govt. Job.

Both exams are difficult to clear but UPSC is harder.

I hope this helps.
Regards
Madhur