which collage is better for mechanical...either IIEST shibpur or i shoud go for BIT Mesra??

Overall IIEST is outstanding college but if we compare the placements than BIT Mesra offers better placements.
You can also compare both the colleges from the given below link
http://www.engineering.careers360.com/bengal-engineering-and-science-university-shibpur/reviews
http://www.engineering.careers360.com/birla-institute-technology-mesra/reviews
Good luck!!
