I would suggest IIIT Lucknow because for branch IT has got a better placement opportunities as compared to mechanical in India.

The higest package offered to IT was around 30 lakhs per annum where as in NIT. Jalandhar highest package for mechanical was 20 lakhs per annum

IIIT Lucknow being a new college got its first batch placement so well so you dont have to worry about the placements there.

For more information you can visit :

https://placements.iiitl.ac.in/#...

Here the choice of branch is most important, choose the branch you have interest in. College can give you only a good start rest is in your hand how good you are in your stream.

Opt for NIT Jalandhar as it has national institute tag with it as well as you are getting a core branch that is Mechanism engineering. The placements are also fine enough. Besides this, you should go for the subject or course that you feel you can handle for four years. If you stumble in between then there's no question of good placements.

Hope this helps.