Hey,

Both of the colleges you provided are amazing and have great placements and faculty no doubt. But if you have to make a choice between them then go for MNIT Allahabad.  The course fees for MNIT is comparatively lower than that of IIT patna for btech. Even though the fees structure is low the placements are amazing and is higher than that of IIT Patna. Also seats offered in MNIT is more than IIT patna.

Well i am providing you with a link below which will help you to compare both the colleges based on different parameters like ranking, placements, faculty and more -

Https://www.careers360.com/compare-colleges

Do visit the website for a clear and better idea before making a choice.

Hope this helps.