Since breaking through as a pop star with her Control album 40 years ago, Janet Jackson has amassed one of the great song catalogs in pop or R&B history. Of course, she’s racked up hits like few other artists before or since — including 10 No. 1 hits on the Billboard Hot 100 , as well as 27 top 10s, all achieved within a 15-year run of staggering chart dominance — with far too many widely beloved classics to even fit all of them into a live setlist. But she’s also released decades of albums whose highlights extend well beyond the singles, with fan favorite deep cuts and remixes that match her stratospheric heights with equally impressive depth. While Ms. Jackson’s legacy extends to all corners of pop culture — not just iconic music videos, tours and performances, but also into the worlds of television, film, fashion and dance — today, we’re focusing on the songs. To celebrate her upcoming 60th birthday (May 16), we’ve assembled our staff’s picks for Janet’s 60 best songs.…