Frigg, Thor Granddaughter from the future, in favor she is blond is lips match the female Thor pics, she is a warrior, she is Asgardian, she's a creation of Jason Aaron himself, against a time travel could make the plot confusing, and in a future spin off would be more difficult explain why she should remain in the past.

Valkyrie, in favor she is a great warrior she also is Blond, against she would be to obvious and its an already establish character of Asgard, she isn't in Jason Aaron current run.

Jane Foster, in favor she is struggling with cancer and in Thor God of Thunder issue 24 she went into space with the Asgardians, against she has brown hair and she is not a warrior, she is not Asgardian.

Agent Roz Solomon, in favor she is determinate, and she had been in the center of the plot of Thor The God of Thunder last issues, against she is not blond, she is not Asgardian.

Sif, in favor she is an Asgardian warrior that born blond, against a key character to Asgard and Thor, that It's hard to change, she isn't in Jason Aaron current run.

In my opinion It's Frigg, but i would like to mentioned, this is only a marvel female publicly stunt, that Marvel Comics put above Thor Character disrespecting him, and his past, and his fans like me. Thor is not a mantle it s a Scandinavian male name that marvel didn't create.