I have been using ICICI Bank for over an year now, and have found it to be quite good - I have accounts in HDFC, UTI, ABN AMRO.
The account opening was the fastest - they had the kit with them when the representative came in to get the forms signed.
The experience at the branch (I went to NFC, Delhi) was one sore point - the employees could have been more helpful.
One thing I reallly like about the bank is their website - its as much as you can ask for from a bank website. Besides the normal things like viewing your account status, ordering cheque books, downloading statements etc one can also pay bills. I have used it to pay for Airtel, LIC, ICICI Pru.
The best option for a very busy person like me is the facility to do interbank transfers. The back bone of this is implemented by RBI. I am able to send money to any any bank in any metro through this site. I used it to pay my rent, and it saved me the trouble of sending or depositing cheques. This facility is not provided by any of the other banks. All other banks only allow transfers into accounts of the same bank.
The ATM experience has always been good - I have not yet got a non-working ATM for this bank, though I have had to stand in long lines close to paydays.
Over all experience, I would rate HDFC as the best among the banks in which I hold an account. ICICI would come in second.