Despite the ability for some channelers to wield greater quantities of the One Power, magnitude actually doesn't correspond in a one-to-one relationship with increased quantity. Aes Sedai, for example, despite their various levels of strength, are not able to handle large volumes of Air the way Windfinders are, because their training favors more discrete weaves. Elayne and Egwene, for example, were far stronger than any Windfinder they encountered - yet manipulating Air and the weather in such a large amount was not something they were trained to do. And Mesaana's own comment was that Semirhage was not that skilled at weather manipulation, despite her increased strength.

I think this is why the Forsaken often comment on strength, but don't use the same distinctions an Aes Sedai does. To them, strength is not only what you are capable of channeling, but also what you are able to do. The only times we've seen someone get overwhelmed, for example, we see that they are not destroyed out of hand - they actually have the ability to assess the situation and/or retreat. And we've seen the Forsaken, with various levels of strength confront mixed sex Circles, which greatly increased their odds of being overwhelmed. Yet the only Forsaken to be destroyed was the least brave and capable among their number, despite the fact that they undoubtedly were no match in quantity of the One Power for the Circles they faced. If strength really was the be-all-and-end-all, the Forsaken would have been Shielded by the Circles and imprisoned, yet the only time a full Circle tried this, they were rebuffed and put on the defensive.

It seems to me that experience, training and skill plays a huge factor with Talents and affinities combined making it even more difficult that trying to over-simplify things in favor of one or more factor is just going to miss the point. Access to greater amounts of the One Power make it easier to accomplish things, but there are multiple ways to achieve an effect.