I like Roudybush best because it's a 100% complete diet, which is why they tell you fruits and veg are just a supplement. Its fine to offer a mix of things, just don't over do it because they may overload on certain vitamins/minerals.
When I first started working with birds, the breeder I worked with only offered Roudybush. In the pellet world, at least what is available down here, Roudybush and Harrison's are at the top of the list for high quality and highly recommended. The difference, really, is that Harrison's is organic, Roudybush is all natural. Harrison's is also twice the price, and I really don't see any difference in quality between the two, personally. I watched an interview at UCF with the gentleman who created the Roudybush diet and it was fascinating. Roudybush isn't just a diet, it has probiotics incorporated into the food
A lot of people can tell you, on most seed/pellet diets they have to offer probiotics regularly because it upsets their digestion but I've never had a problem with that while feeding Roudybush. They also do a lot of work on trying different diets. They have food mixes for birds with specific health problems - rice formula for birds with allergies, formula for birds with liver problems, formula for birds with PDD, etc. I've used this food for... 8 years now and I would never go back
I feed my little birds a mix of 60% Roudybush, 40% high quality all-natural seed (Goldenfeast) and they get fresh fruit/veg everyday
Goober gets 80% Roudybush 20% dried fruit/nut mix with fresh veggies every day (minimal fruit because she has the dried fruit already) because Macaws need a higher fat diet than other species
Everyone does fantastic on it
The vet always gushes over the linnies and Goober because their feathers look so nice and they're always right on target for weight. Obesity is a problem right now with parrots, apparently