I have been a customer of hdfc bank for over 10 yrs. Its been a good experience with them till now. I prefer to use this bank because of the ease they provide to the customer. When I changed cities it was very easy to close an account, open a new account and transfer money from the old account to the new one without too much fuss.
Most of the transactions can be done online. You do not need to go the bank. For eg you can open an FD, request a cheque book, etc online.
The best thing I like about the bank is that as soon as you do a money transaction you get a mail and an sms about it.
I have interacted with customer service and it was good.
So overall I am a happy customer