Hi,

I would suggest that you should choose your course over the college. GMRIT has good infrastructure though it's studies and placements are average. At the end, it is you who has to study yourself. If you like the branch, you will feel like studying and you could score well. You may also aim for PSU jobs by giving GATE. Mechanical is a good branch to pursue if you have interest and it has plenty of opportunities. 

The final call is yours though. All the best!