what should be the order:

mechanical iit rooorkee,

production and industrial iit delhi,

electrical in iit roorkee.

The answer completely depends on your interest.

But if it would be me then I would take

1. Elec at IIT-R

2. Mech at IIT-R

3. Prod and Ind at IIT-D

Again first decide whether institute is more important to you or the branch.

Also keep in consideration the kind of city you want to be in. If you want to go for a MBA or a Civil Service coaching then take a big city. And if you want to go for a job or further studies like an MS then take a good branch of your choice.

Hope you can take a good decision.

Dear nikhi Khuttan

keeping an eye on all factors such as placements, prospective facility etc the order of colleges is 

IITR Mech

IITR ELEC

IITD P & I

Best of Luck 

Hope this has helped you!!!!!