In general, I would advise against it, unless you have a very deep knowledge of game systems, multiclasses are usually weaker, because you lose spell progression etc.
Otherwise, the obvious contenders are all the cha based classes, in particular Paladins, with at least 2 levels (better armor proficiencies, smites, ...) and warlocks (esp. with pact and the blade, and for eldritch blast + agonizing blast)
