barm - the paed was probably right. Aptamil prob is 'most popular with parents who want to bf'...this is the result of marketing and promotion, and of course price-pitching.
It is no good for manufacturers to produce 2 virtually identical products (Aptamil, Cow&Gate) both chasing the same market segment. You need to differentiate your market, to avoid all your strategies being in competition with each other.
Aptamil is posh formula - their packaging and their pricing differentiate it from Cow&Gate.
Aptamil looks cool, modern and sophisticated. It is a brand of milk only, not baby food. People's mothers did not use it as it has not been around that long.
Cow&Gate is in marketing terms a 'heritage brand' (like Daz, Kellogs Corn Flakes, Domestos) which has been around forever, and which people remember from their own childhood and which their own mothers used. Cow&Gate is also branded baby food. So, a powerful brand with a mass appeal, with bright colours on the pack and a lower price point.
Different people 'go for' different brands (obviously not totally consistently - I am talking trends here). The posh mother who wants to breastfeed and who has maybe not so much faith in formula feeding and who feels a bit wobbly about even using it, can be 'reassured' by the 'feel' that Aptamil gives her.
Cow&Gate sells itself, because of being a heritage brand; all it has to do is to look like itself. The target market is mothers who formula feed from the start, or near the start, and who don't feel a bit wobbly about using formula.
No one has to be stupid to fall for marketing like this. All you have to be is human.