See as per the information of placements, the placement percentage is much more for Techno India Main compared to GNIT. In case of Techno India the placement for CSE is >87% and compared to that of GNIT its 67%. So to have better possibility in terms of placements go for Techno India Saltlake. Apart from that there are no such big difference among this two colleges which influences a lot in your career except this key factor. Both of the colleges are academically good and infrastructure is also good.

To know about Techno Main visit:

https://www.careers360.com/colleges/techno-main-salt-lake

To know about GNIT visit:

https://www.careers360.com/colleges/guru-nanak-institute-of-technology-kolkata

I hope this helps.