Quote from def:
There are a number of brokerages who I personally would call safe but I can only speak for IB but I'll let IB's financials speak for itself and would encourage anyone considering IB to review our financials.
Somewhat related, have you checked out the share price of many of the bank stocks lately? Do you have any concerns about about off balance sheet items? I'm assuming the market knows something and that there is a reason many of the banks are trading well under book value. Do that research and you might remove 2 of the names off your list above that you consider so safe.