For me, good singers don't always make better music. But Beyoncé defies that, she is a well rounded artist and her music is flawless. 4 alone is her best body of work to date.
I use both 4, Self Titled and some songs from B'Day while I don't care for any of Rihanna's efforts, although I find ANTi cute and she has nice singles to an extend.
Rihanna's is just generic pop, and the albums are mostly filler other than the singles. Beyonce's discog is better in every way, 5/5 albums are flawless
Also ANTI drags Rihanna's discography down quite a bit