I tried Harrison's with Rio back when I first got her, she would not touch it after she tried it once and quickly spat it out. It ended up being a waste of money for me, which is a shame because I know its an amazing food!
I have tried Zupreem and she will eat some of it but only the green ones and the banana shaped ones haha. I also dont like how it has added sugar. I havent tried Kaytee yet however.
Right now she is on a mix of 50%-60% Tropican pellets and the remainder is seeds, nuts, dried fruit, legumes, dried veggies, etc. And I put 3 pellet berries in her dish in the morning. I think she is bored with Tropican pellets now (or maybe they have changed something slightly?), the last little while I have found she has been flinging most of them out of her dish. I think its time for something different.
She LOVES nutri-berries, I give them to her as a treat.
Of course she gets fresh stuff every day too, right now consisting of apple, corn, peas, blueberries, and cooked oatmeal. Next week will be mixed veggies and brown rice.