I'd suggest to buy the Daily Sweet deal just because you recieve 2x 5 Star medals and 3x Cid whereas you recieve 1x 5 Star medal when buying the Wicked deal.
When buying the Daily Sweet deal you also have the chance to obtain wicked medals.
But honestly I'd wait for the next event (probably Organisation XIII medals) to come before spending my medals. Atleast that's what I'm going to do