I think "choosing for two" is a bit cryptic, tbh.
I get irritated by the "breast is best" slogan because I think that breast isn't "best", it's normal (at least from a biological viewpoint). Formula is an adequate, but inferior, substitute.
Mass media messages motivated by commercial interests, have normalised formula feeding, so that breastfeeding is considered to be ?better?, something to aspire to. The language surrounding breastfeeding often speaks of the ?advantages?, ?benefits? etc. The popular slogan, ?breast is best? exemplifies such comparison, where something else is normal, good, better and then at the highest level, there is breast feeding ? the best. In other words, the "best is breast" slogan implicitly suggests that bottle-feeding is the "norm".
Not got any great ideas for slogans, but wonder about something emphasising the place bf plays in the natural continuum of child-nurturing. "The natural choice"... perhaps something along those lines.