Kota is considered to be having the best coaching classes in India but it is because of the students that they are the best and not because of the faculty. Though while choosing a institute I would be a little biased towards kota institutes because I have studied there but apart from it there is another reason that the faculty over there is very experienced and also has many iitians so they can guide you very well.
But again it is more about you being more focused and working hard. If you choose kota for coaching you should better opt for Vibrant or resonance because they the best for iit.