I got a call from IIT Bhubaneswar as well as from IIT Gandhinagar for MTech in Machine design branch. Which IIT is better?

 I think you should go for M.Tech in Mechanical Systems Design at IIT Bhubaneswar. IIT Gandhinagar offers an M.Tech in Mechanical Engineering, but not specifically in Machine Design. 

IIT Bhubaneswar is placed #47 in the Engineering category as per the NIRF 2023 Ranking. The School of Mechanical Sciences at IIT Bhubaneswar has fully equipped labs. It has a state-of-the-art computing lab with thirty workstations connected to an eighteen-blade server.

Here’s a comparison between IIT Bhubaneswar and IIT Gandhinagar:

(The M.Tech placements data is not available for IIT Gandhinagar)

Although IIT Gandhinagar has a slightly higher ranking than IIT Bhubaneswar, the Mechanical Sciences Department at IIT Bhubaneswar has a much better overall value. 

I would recommend you choose IIT Bhubaneswar Mechanical Systems Design over IIT Gandhinagar Mechanical for your M.Tech degree.