My trainer breeds Wheatons!
A rare breed, but starting to get more popular, it's not even my dog but I love to brag up my trainer's accomplishments, her dog won BIS at the terrier speciality here in Ontario, Canada!

Had to put it out there! LOL
Toller mentioned some great brands, all of which are known to be "higher end".
As for formulas, most breeders I know of, do NOT feed puppy food. There's no need for it. For instance, most of Eagle Packs formula's are for all life stages, and are fine to be fed from puppyhood until their senior years.
I feed Eagle Pack, and I know recently they've come out with a power formula, for dogs who are considerably more active. May be something to consider depending on the amount of excercise.
I like all the brands Toller listed, specifically Solid Gold and Eagle Pack. Mainly because they are the higher brands that are available to me.
Royal Canin IMO, is in the middle, between Iams and brands like Solid Gold.