Best College for Physics in India
It's a little bit of a tricky issue. Of course IISc is a very good research institute, definitely among some of the best institute in India for research, but undergraduate level teaching and the environment is a little bit of a different story that you should keep in mind.
University of Calcutta (CU) have some the best undergraduate colleges in India for doing BSc Physics (Hons). And this is very clear from the fact that till today in India alone the University of Calcutta have the 2nd largest number of students every year that clear (pass) the national PhD studentship/Lecureship (NET/CSIR exam) in Natural Science (Physics, Chem, Math etc) and get admitted in PhD in India's best research institutes (See here CSIR-UGC Central Govt document : ). Its astonishing that even having so many Universitites in India, just only four University from Bengal (CU, JU, DU, KU) together has the highest share of the students within Indian that clear the CSIR-UGC PhD fellowship in Natural Science. Also remember most of the faculty (in Physics and Chemistry) in all serious natural science research Institute (like TFIR, IISc, IACS, IISER) in India are from University of Calcutta or from other University (BU, JU, KU) from Bengal.
Being the first Physics dept created (1914) not only in India but also first in Asia (and completely unaided by the British Govt) by visionary and subsequently chaired by famous luminaries like , , , and others, it has a long history, first and only Nobel Prize in Physics in India, several prominent Royal Society fellows (FRS) and lumenaries (, , and others) continued tradition of creating and maintaining great teachers, great Physics practical laboratories (the best in India), largest alumni base in Physics that spread all over the world and India. Remember even in todays India, the most famous Indian Physicist studied in University of Calcutta.
But its very quite difficult to enter there as its kind of insulated from the the students from the other states. Only Bengal's students can enter there (kind of) mostly based on Higher Secondary marks and interview or sometime (rarely) based on entrance exam.
IISER are just started and its mainly evolving as serious research institute but still it does not have good name in teaching, rather the common experince is pretty negative, I would say till now stay away from IISER (but thats my personal opinion).
ISI, CMI, IIT, NISER, BITS all these instutute rightfully have footstep in their own specilaization (like ISI in Statistics, CMI in Math, IIT in Engg..) but not anything specially for Physics. Rather I would say TFIR should be in the first place in this list (if they provide BSc at all), IIT Kanpur has very good name in Physics (specifically for MSc). IISC so far I know dont give BSc (Physics) degree but a 4 year BS but that should be a serious good program.