Lewyn Martell was true steel, Aerys Kingsguards were a team of badasses. Jaime takes pride from having learned from every one of them, Lewyn included. I'm not sure if Lewyn was weaker than Oberyn at all frankly.
Anyway, the Targaryens win. I would say that either Targaryen warrior is better than either Martell, and they even have Valyrian steel.