What are the best banks in Bahrain that offer current accounts with the highest possible interest on balances, and how do leading banks such as National Bank of Bahrain, Bank of Bahrain and Kuwait, Standard Chartered Bahrain, and ICICI Bank Bahrain compare in terms of features and benefits? Additionally, given that most current accounts in Bahrain typically offer little to no interest, what key factors such as fees, minimum balance requirements, transaction flexibility, and digital banking services should customers consider when choosing the best current account?