Well, brother I firstly would say you have two great choices at front. 

Regarding, the above choices, since both having similar domain

I would simply say to prefer IIT KGP over NIT Trichy

Reasons 

Campus Life at IIT KGP > NIT Trichy

College Fest IIT KGP > NIT Trichy

Placements IIT KGP > NIT Trichy

Peer group IIT KGP > NIT Trichy 

I think, I've made my point enough clear

Thank You