The past twelve years, the only artists to have sold over 1M in a week are: Full List:
Taylor Swift (x2)
Lady Gaga(Cheated Selling Album for 99 cents)
Limp Bizkit
50 Cent
Eminem
Britney Spears
Norah Jones
Lil' Wayne
Backstreet Boys
'N Sync
Usher
Garth Brooks.
Considering Taylors done this twice now, probably puts her in the top 3 of these
(I'm sure like a few of theese may have done it twice aswell, Assuming Eminem/Lil Wayne.)