You can't compare those two, they are apple and oranges even if that sounds strange.

Central bank digital currencies are going to replace cash, they won't be an alternative to a digitally represented fiat. A transaction that is done via your bank is an IOU-based. CBDCs won't have any difference from cash other than humiliatingly bad privacy. So, it should be properer to say that CBDCs have disadvantages over, say Bitcoin.