Lanfear's strength level on the female side seems to be far more freakish than Rand's strength on the male side.

Among the male Forsaken, it seems that Rahvin, Sammael, Aginor, Demandred and Ishamael are all very close to Rand's strength level.

In contrast, there is a significant gap between Lanfear and Graendal for example, large enough for Cyndane to fit into.

And Graendal herself says it was very rare indeed, even in the Age of Legends, to encounter a woman that exceeded her in strength.

So even Cyndane's level is extraordinary in Graendal's view. Lanfear therefore must be an absolute freak.

So how do we solve this discrepancy on the female side.

The following model, solves it, in my view, and also agrees with all the evidence we have thus far.

Lanfear
Cyndane, Semirhage, Alivia
Graendal, Mesaana, Nynaeve
Moghedien

That puts Lanfear at the top - check.
It puts Cyndane above Graendal, but weaker than Lanfear - check.
It puts Nynaeve equal to the average female Forsaken - check.
It makes Alivia stronger than Nynaeve - check.
It makes women stronger than Graendal very rare indeed - check.

It allows Mesaana to state that she compares relatively well with Semirhage, although some (unnamed) WEAKNESSES in her own repertoire is balanced out by other (unnamed) strengths she has over Semirhage - check.

I favour this model, and with the current evidence, it is as feasible as the one which puts Graendal higher than Semirhage.

What my model also does, is it reduces the gap between the majority of the female Forsaken and Lanfear. Because by reducing Graendal's level, it means Cyndane's level is also brought down, as the only comparison we have between her and the other female Forsaken is that she is stronger than Graendal.

To me this is a neater explanation.

Now, Cyndane is just one level above Mesaana, and at the same level as Semirhage, who in turn is just one level below Lanfear.

This makes the overall spread of the female Forsaken tighter. Which would make more sense, I believe.