You'll no doubt get a bunch of different answers to this one - but here's my two cents.
If you value the security of your members' personal details;
If you value the security of your financial transactions;
If you want something that will conform exactly to your specifications;
... then you will need to write something yourself or commission someone to write it for you.
Unfortunately the list is pretty bare. Joomsuite Member is likely your best choice but it's encrypted and requires their activation server to be online for your component to continue working. You can find it here:
joomsuite.com/index.php?option=com_resou...&article=15&Itemid=9