It depends on the bank card issuer.
any card limits?
You are just selling cards from 4 banks.
Is that so hard to post the limits for 4 banks?

Without knowing the limits it's hard to know which is the best but I'm interested in millennium bank because I also have this bank in my country and I guess it's better if I need to solve any problem.
Please tell me the limits of millennium cards (and others too if possible).
Another question:
Cards have limited validity. Will the account remain open after the card's expiration date?
Do you have cards in stock?