When I had a resonator (Recording King Concert Reso), I strung it with a Low G. For how bright and shrill the instrument itself was (mine was completely metal, so that played a part also), the low G helped to bring some body and depth to the instrument that re-entrant tuning didn't have.
As for strings, I had a set of Aquila that came on it, and all I did was throw on a wound G string. Later I switched it to some black nylon with a phosphor bronze low G, and that warmed it up a bit more.