Congratulations on your new pup !
Lesson 1: two 'dog people' are only ever going to agree on one thing: that the third 'dog person' is doing everything wrong.
Lesson 2: like cars, dog food brands come in 'classes' and, within classes, which one to go with is largely a matter of personal preference.
Among the top class (BMW, Mercedes, Lexus): California Naturals, Innova, Solid Gold, LID (Limited Ingredient Diet), EVO, Healthwise, Mother Nature, Karma, Wellness, Blue Seal, Organix, Eagle Pack and Canidae.
Middle Tier (Toyota, Honda, VW, Ford): Nutro, Science Diet, Costco (Kirkland)
There is a pretty wide price gap between those two tiers and between them and the bottom rung (pretty much anything you can buy in a supermarket).
The general rule of thumb is that you want to avoid anything with wheat in it and anything like 'animal products', etc as others have pointed out.
Two of my three dogs could probably thrive on anything. The third has a very delicate gut and was almost killed a year ago when a manufacturer changed the formula of their food and didn't announce it. For a while I had two of the dogs on a lower cost food and the sensitive one on a single-protein no wheat kibble. Then I became worried that a mix up in the food bowls could kill the one with allergies and put them all on the 'higher grade' more expensive food (California Naturals Herring and Sweet Potato.
Your vet mentioned Diamond because they were at the epicenter of a 2005 nightmare in which melamine made its way into animal meal from China. A number of dogs died and many more suffered severe kidney damage. I have several dog trainer colleagues who continue to use Diamond food because ounce for ounce it's one of the least expensive high protein kibbles out there.
If you're going to switch from Diamond, you might want to try the Kirkland brand. A rescue I work with uses it with no problems.
Here's a link to a magazine that, among other things obsesses about dog foods. http://www.whole-dog-journal.com/issues/13_2/features/Best-Dry-Dog-Food-Whole-Dog-Journal_16196-1.html
It accepts no advertising or fees from manufacturers. I just looked through my back issues and don't seem to have any of their past annual reviews of foods.
Hope that helps.