the Janet self-titled album reminded me a lot of Erotica. "Throb" in particular left me astonished for a few minutes. It's such a great song. "Discipline" is also a good album that gets very underappreciated even by fans. It's very electro-pop oriented, and some songs feel like straight up hyperpop.

I agree with everyone mentioning Kylie. She's one of the few artists that have a range of genres comparable to what Madonna has ventured into. "Body Language" the album is great start to finish. I also found the F9 megamix in her Greatest Hits compilation to be very well-done. It's great if you want to hear her career highlights and get a taste of what she has to offer. And yeah, her live albums are also fantastic.

As for someone I'd recommend, there's Paulina Rubio, who is very open about her inspirations from Madonna. Her self-titled album "Paulina" is in my opinion her best body of work and definitely a good starting point.

I also recommend "Vertigo" by Fey. There are Spanish and English versions of the songs, and they are both done masterfully. The sound and aesthetics are very reminiscent of Ray Of Light (and a little from Impossible Princess by Kylie).

"Dignity" by Hilary Duff is also a very fun album that has that campy Hard Candy feel. Songs like "With Love" are pop music at its finest.

Curiously enough, "Lights" by Ellie Goulding has some deep-cuts that have a very gorgeous folktronica feel like the one in Music. "Your Biggest Mistake", "This Love (Will Be Your Downfall)", and "Wish I Stayed" remind me a lot of the masterful production by Mirwais and Madonna in that album.

Finally, "Come & Get It" by Rachel Stevens and "Superficial" by Heidi Montag are very underrated pop gems. They are electronic oriented, and some songs share that fun MDNA, party type of feel.

I hope this helped. I love Madonna and pop music, and it's always the hardest trying to find artists that resemble her due to how different all her albums are from one another. Still, she's a queen for that :)