Probably GGGB. Loud is a close second but I think during that period people were confused about all the Rihanna eras, whereas GGGB being the one where she broke out, it was more memorable.
Toss up between Loud and Good Girl Gone Bad. Rated R should be up there too, but because it flopped (compared to GGGB and Loud anyway), I doubt it will be.
GGGB - Loud was when Rihanna was making her best music, in my personal opinion. TTT is OK (WFL slayed and I BOP to Cockiness), but Unapologetic is awful. Again, just my personal opinion. And the least said about the two mixtapes the better.
