Try searching YouTube for some comparisons.
I've found some comparing vintage 10Ms to vintage Selmers. That same guy also did the same for the Bari Saxes. Even found one comparing 1930's 10M to a Post WW2 10M. The 30's 10M sounded a tad better and the Conn's over all had a better tone than the Selmers IMO. FWIW I do have a New Wonder Alto that sounds exceptionally well. Sorry haven't looked for any YouTube videos on the Alto.
I've found some comparing vintage 10Ms to vintage Selmers. That same guy also did the same for the Bari Saxes. Even found one comparing 1930's 10M to a Post WW2 10M. The 30's 10M sounded a tad better and the Conn's over all had a better tone than the Selmers IMO. FWIW I do have a New Wonder Alto that sounds exceptionally well. Sorry haven't looked for any YouTube videos on the Alto.