I refered the Ignis ICO as a mediocre crowdsale, with unhealty token distribution and the NXT pump prior to Ignis airdrop as a manipulation. I did not address the quality of their blockchain.
Ardor and NXT seem technically potent to me. The former has childchains, the latter works great as a ledger with decent throughput. I can easily see banks conduct feasibility studies or test adaptation of a blockchain to perform internal functions - ERP, CRM, asset management.
I don't know what banks are you talking about, but I am not sure any bank has yet decided to actually use any DLT on a permanent basis, replacing traditional systems.
IMO, NXT/Ardor is simply more suitable for banking activities due to the increased auditability.