The two models are not very different in size – only 3 absolute cup sizes apart (36DDD -> 38DDD -> 40DDD -> 40G). So why did they come up with such different rankings? One of the bras, Sierra FlexWire™ Balconette, is the most supportive bra on Toni’s list, and the least supportive on Ellie’s list.
The answer is a bra has to fit you well to be supportive. Toni and Ellie have very different breast shapes. There isn’t one bra that could possibly fit them both well.
Toni’s shape: very short roots, wide roots, medium projection. The feature of her breast shape that stands out the most is short roots.