Well, it's great that you're trying to give him a proper diet!

Not many people care, and diet is extremely important to avian health.
First off... his diet should be about 30-50% in pellets. Totally Organics, Harrisons, Roudybush, Goldenfeast are the best pellets on the market. However, many birds like Zupreem because of the high corn/sugar content as well as the colorful artificial dyes. You can try feeding Zupreem Natural first, and slowly transition him over to Harrion's or Totally Organics pellets (TOPS).
Kaytee is considered unhealthy and Hagen Tropican has a weird perfume-like smell that's VERY strong. So stay away from those two. Remember, the lower quality pellets are NOT cheaper than the healthiest brands out there.
www.mysafebirdstore.com has a LOT of pellet brands, you can look around for price comparison/ingredients lists.
You can try making him bird bread. Look up recipes on google. Or cook him rice/barley/quinoa with vegetables. If you look on the My Safe Bird Store, there are cook mixes as well as a product called "Bountiful Harvest" that is loved by many parrots.
You should sprout your bird seed by soaking the seeds overnight and then rinsing them several times a day, for the next couple days until you see little tails sprouting. Sprouted seeds are loved by seed junkies.
I'd suggest offering different vegetables in different textures. Cut up in little pieces as well as big chunks hanging from the cage.