Abu Musa al Ash’aree narrated that the Messenger of Allaah - صلى الله عليه وسلم- said:
“A lot of men have reached a stage of perfection, but none amongst the women reached a stage of perfection except:
Maryam bint ‘Imraan and
Aasiyah the wife of Fir’aun,
and the virtue of ‘Aa-ishah when compared to other women is as the virtue of meat when compared to stew.” [Collected by Bukharee and Muslim]
The Hadeeth established perfection for Aasiyah just as it established it for Maryam, …the meaning of ‘virtue’ in this Hadeeth has been explained clearly in what was narrated by al Bazzaar and at Tabaraanee on the authority of ‘Ammaar ibn Yaasir that the messenger of Allaah - صلى الله عليه وسلم - said:
“Khadeejah has been preferred over the women of this Ummah, just as Maryam has been preferred over all the women of the world.”
A Hadeeth with a sound chain of narration which was used as evidence that Khadeejah is more virtuous than ‘Aa-ishah. 
Ibn at Teen stated: “It could be that ‘Aa-ishah was not included here because she was only three years old when Khadeejah passed away, so it could be that what is intended by the Hadeeth are the women who reached puberty.”
However this viewpoint is weak, because the word ‘women’ in the Hadeeth is general and encompasses all women. 
An Nawawee states the summary of which is:
This Hadeeth has been used as evidence by those who claim that Maryam and Aasiyah were prophets, the majority of scholars however, are of the opinion that they are not. Rather they are Siddeeqataan, Waliyataan from the Awliyaa of Allaah the Elevated, and a number of scholars have stated there is a consensus concerning this and Allaah knows best.
The term ‘perfection’ is used when something reaches its fullest and most complete state when compared to others like it, and what is meant by it here, is the most complete state in all virtues and all forms of goodness and piety.
The statement of the Messenger of Allaah- صلى الله عليه وسلم- :
“…and the virtue of ‘Aa-ishah when compared to other women is as the virtue of meat when compared to stew.”
The scholars explained; meaning the meat in any dish is more virtuous than its stew…and what is meant by its virtue is its benefit, being satisfied by it, the ease of digesting it, its delicious taste, and the ease a person finds in eating what he needs of it quickly and so on, so it is better than all the stew, and all other types of food. ‘Aa-isha has excess virtue when compared to other women just as meat has excess virtue when compared to stew.
There is no evidence in this Hadeeth that ‘Aa-ishah is more virtuous than Maryam and Aasiyah, because of the possibility that what is meant is her virtue over the women of the Ummah. 
 The scholars have differed as to which of the two is more virtuous, the preponderant stance being that each one (including Faatimah) has virtues over the other from different angles, and concerning the mention of other women in different time periods, then each one was the most virtuous during her time period and one should not delve into which one is better than the other. A more in depth look a the most virtuous women can be found here.
 Fat-h al Baaree: Vol. 11 P. 130
 Sharh Saheeh MuslimL Vol. 8 P. 180