Getting a Lab pup in about 3 weeks and I am curious as to what everyone feeds their pups and for how long do you keep them on the puppy food?

Right now they just started eating their puppy mush which is Eukanuba. I had a conversation at a pet store the other day and was told there are a couple key things to look for. One, corn should not be one of the first 4 or 5 ingredients, if it is, you are paying for too much filler. Two, the meat should be identified as being beef, chicken or lamb, it should not just say meat or bone as this is lesser quality, and third if possible it should be some sort of meat "meal" as your not paying for water weight then. He basically destroyed their own brand that they sold touting it as junk. After talking to him and looking at a bunch of different brands, I was amazed at how many have corn as either the first or second ingredient. He pointed me towards Nutro Natural or a Diamond product.

What are your thoughts, was he right on or was it BS, and what do YOU feed?