Just my guess:
Nintendo Switch vs Nintendo Wii'10 (17.2M) --> Wii will win (but it will be rather close)
PlayStation 5 vs PlayStation 3'11 (14.7M) --> PS5 will win (by a few million)
XBOX Series S/X vs XBOX 360'08 (11.2M) --> Xbox 360 will win (by a decent amount)
Nintendo Switch vs Nintendo 3DS'14 (3.2M - JAPAN) --> Switch will win (They will basically be even. Nintendo Switch will win by an tiny amount)
PlayStation 5 vs PlayStation 3'09 (1.8M - JAPAN) --> PS3 will win (but it will be close)
XBOX SERIES S/X vs XBOX ONE'15 (5M - USA) --> Xbox Series will win (I have absolutely no idea about that one to be honest^^)