It's very easy when you look back in time ...
The same way people NOW say that Rihanna's sales have always been consistent, whereas I remember in 2011, 2012 she was always dragged for her low sales (3M average WW)
The same way people NOW say that 4 by Beyonce and RR by Rihanna were not flops, whereas at the time they WERE.
The same way now people think 2007 was Rihanna's year, whereas GGGB wasn't even top 15 best selling album at the time
It's way easier when years have passed, isn't it ?
ARTPOP won't be considered a flop in a few years, mark my words.
So yeah GGGB had more impact (because it had its time to actually have impact) but success ? No. 1989 is more successful as proven by that post that shows the year end peaks etc.
And who knows, maybe in a few years 1989 will be considered iconic and impactful.
So in other words - Bad comparison