In terms of management l, ARTPOP by far. Like, the Venus-DWUW mess, the Applause vs. roar mess, all the negative press, she lost her manager a week before the album was released and took a three month blackout in the middle of the era then try to revive it in the spring, only to basically shoot herself in the foot with G.U.Y.
I love ARTPOP so much but it was a mess from the ground up. It deserved so much better

I dont really see what's so messy about the R8 era. I mean it's not as successful cause it's not your typical Rihanna sound but that's clearly just the direction she's going in