What are options for finishing cement block walls?
I would seal the blocks first using a penetrating waterproofing sealer.  Silane/Siloxane sealers are excellent choices for basement concrete block.   Okon’s S-40, Diamond Hard and Lithi-Tek LS 9500 are some excellent products.  Stay away from latex based sealers.  I would also fur out the walls so I could add some insulation, run electrical, cable, internet and plumbing. You can now finish the walls however you chose.