Amazon has started letting us peek into the Companion, and I've used the search function to get the strengths of quite a few women. Some real doozies in here including:

Rahvin was as strong as Rand or Ishamael. Semirhage was as strong as Lanfear, as was Alivia. Mesaana was level two, and one level above Graendal and Nynaeve. Equal to Mesaana are Cyndane, Talaan (potential) and Sharina.

Nynaeve's current strength is level 4, the same as Moghedien's. And then comes the craiest wildcard: Cadsuane is level 5, and stronger than Egwene.

For some reason, Aviendha's entry says her strength is level 11, though Terez says it is most likely her current strength, with her potential equalling Egwene's. Since I can only read snippets, I'm hoping this is what they mean.

Another surprise is that Edarra matches Therava, and both are at level 12, one above Siuan co. Kerene was level 11, Meilyn level 10, and Mabriam en Shereed, along with Metarra and Nicola, at 9.

Caraighan Maconar is at level 3, matching Nynaeve. I would speculate this was the highest level the Tower ever saw, before Sharina.

Liandrin is the same level as Leane was (14), just one below Elaida, which came as a surprise.

A surprising number of Sitters and influential Sisters are in the 17-24 range of levels, putting paid to the idea that only the strongest were influential.

Level 19 is the base level to be able to Travel. Level 21 is the base level to make a Gateway of any size, without a circle.

Here's a Google doc link where you can comment:

https://docs.google.com/spreadsheets/d/1LgUvi6JyRrikxm6jiRUwQlTFo64Hz2X7ng9ucZSWWfY/edit?usp=sharing

If you have any more strength values you can glean, PM me and I'll send the editable link.