Hello student,
To speak generally obviously Mumbai is better than Lucknow but if you are talking about any particlar course then do let me know so that I will elaborate on it. So talking about mumbai there are many good colleges available like IIT Bombay, TIFR, DY patil, St Xavier's college, SNDT etc. Also traveling though it is crowded but there is good connectivity available. Also there are many good coaching classes around just in case you need any. Though mumbai is expensive than lucknow you can manage expenses once you are sure abour your college and the duration of your academic course. Lucknow too is a good city having many good colleges. So ultimately it depends upon your course and marks too.
All the best and thank you
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