Unless you're adding to a brooder that already has chicks I'd get 3 : D It just tends to work better, in case of roosters, illnesses, a bad attitude chicken, etc, plus they really enjoy eachother company! Brahmas are bigger, both have small combs (good if you live somewhere that they could get frostbitten) both tend to be fairly docile, and both have basically the same coloration (columbian). Wyandottes have sort of that 'heart shape' or 'tea pot shape' which I personally love, and Brahmas have feathered feet (which can get muddy or messy, but not too bad). I'd personally get one of each, and then a third chick : D