Von Cramm vs. Nüsslein would be a fine rivalry. The only pro-am match at Blau-Weiss Berlin was won by von Cramm in four sets. From all the pre WW II players i have seen on clips, von Cramm had imo the most modern style, alongside Vines. I must say, that i haven't seen much of Nüsslein. In Germany, most experts like Menzel or Kleinschroth rated von Cramm as the best German pre WW II. In the 30s i find it extremely difficult to rank amateurs and pros combined, since the mid 50s it is easier to rate the top pros over the top amateurs. Von Cramm and Nüsslein would have been a fine Davis Cup team, to challenge the Brits and the US: von Cramm other companions had quite short careers, Daniel Prenn went into exile very soon, and Henkel, who died on the Eastern front, wasn't yetl at his peak, when the war began.