Hello Aspirant,

Since you have mentioned research , definitely is better to go for B.Sc Physics.In engineering you will be learning the basics of branches like cse,eee,ece,mech etc in the first year and then later more on the specialization you have chosen. There will be a wide range of subject you will cover in those 4 years, and physics as a theoretical subject will not be focused . Engineering is the application part of physics. If you want to get into research area you need a very deep and advance level knowledge in theoretical physics and so many other sub fields which will come only if you take up B.Sc , M.Sc followed by a PhD. You can become a physicist after engineering too , for that after engineering you should take up MS.c Physics and continue till PhD. But see to it that you cover all the basic important theoretical concepts before taking MSc , without which you will find it difficult to grasp. And the engineering branch is not going to make much difference  , because anyways you will be studying the theoretical part, you will be gaining more of only a working knowledge of physics but if you really want to B.Tech degree with importance to physics , go for engineering physics in IITs.

Below are some good colleges for BSc physics

Indian Institute of Science

All top IITs - Indian Institute of Technology Bombay/Delhi/Kharagpur/Madras

Aligarh Muslim University

Banaras Hindu University

University of Delhi

National Institute of Technology Rourkela

Savitribai Phule Pune University

All the best