The word 'best' is subjective in nature . Some students might like one faculty but others might not. Therefore the more views you take the more confused you will be and the more you will delay your preparation. I would suggest you to enroll in classes having decent faculty and also consider some other factors such as the distance between your home and the coaching centre etc as travel time does matter alot. For CAT coaching is a support system but what matters is your own efforts.

Some of the renouned coaching institutes are TIME Ahemdabad and Career Launcher . You can even take online classes for CAT preparation and in that case location won't be a constraint for you.