You have got a very tricky option to deal with.
Look electronics at nit suratkhal is a very good option indeed.
Now listen to this carefully, Go for engg physics IF YOU like physics.Stop listening to people.Close your eyes think about it.Do u see urself doing research in physics. Do you like to study physics for the rest of your life.
You have to understand that when u pick specifics fields like these you must be in mood to do masters and beyond. There will be alot of scope for this but you wont go anywhere with it if you dont LIKE IT.
4 yrs down NOT picking the iit tag wont hurt u that much being at suratkhal but if you pick engg physics at guwahati and feel suffocated by all the pure science topics, you might feel bad about it later.
So pick what YOU think is right for you and forget about what everybody is saying bout it .