Neither of them may be 'iconic', but who is more known and remembered? Who has more memorable moments? Include Hannah Montana in your judgement, as it is a part of her career.
Lady Gaga obviously. Hannah Montana =/= Miley Cyrus.
Hannah Montanah does equal Miley Cyrus, that was part of her career and if Jo can be counted with Lady Gaga then this can. Plus it's no different from any other show.
Miley, hands down. EVERYONE and their mothers were doing the Hoe Down Throwdown dance, EVERY 7-12 year old watched Hannah Montana, EVERYONE jammed out to Party In The USA & Cant Be Tamed. Everyone cried when she cut off her hair. etc.
Neither of them may be 'iconic', but who is more known and remembered? Who has more memorable moments? Include Hannah Montana in your judgement, as it is a part of her career.
You all know Lady Gaga is already an icon. Its a fact
That picture of Gaga too... 
I'm pretty sure it adds to her status.
She's still mainly known for that role.