I've never seen that many people talking about Jermaine's music. He was nowhere near as popular as Janet. Janet appealed to a younger audience than Jermaine. Janet got Top 40 airplay, which Jermaine generally didn't except in a few cases. Jermaine was more the Luther Vandross, James Ingram, Anita Baker, & Freddie Jackson adult R&B audience. Most of Jermaine's Motown albums have never been on CD and have been out of print since they were originally released. They're not on streaming either, other than people posting their record copies on Youtube. No official versions.
How many people compare Mike to Madonna? I've mostly seen Mike vs Prince, in the media, and people in general talking about them. Even celebrities have said either Mike or Prince is better than the other. Madonna is not mentioned. I've also seen Mike compared to George Michael, Terence Trent D'Arby (aka Sananda), Bobby Brown, MC Hammer, & few others, but not really female artists. MC Hammer himself got into this with his 2 Legit 2 Quit music video that James Brown appeared in. I have seen Madonna vs Janet, Madonna vs Whitney Houston, or Janet vs Paula Abdul/Jody Watley.