Harrisons is considered better then Roudybush, HOWEVER, the best pellet is the one your parrot will readily eat. I tried Tops (best), Harrisons (2nd best) and Roudybush (3rd or 4th) but the Roudybush is what he ate, so for us, thats the best pellet. NO sense serving the very best, top quality, $$$ pellet, if it all winds up on the floor or at the bottom of the cage.
What ver you try, make sure a) to change slowly over time. Not abruptly changing foods and b) try to get him to eat fresh veggie "chop", which is hands down the best food for parrots. Chop and pellets as main foods, with a little fruits and even less seed and nuts. Thats what to aim for . Budgies, which are granivores can have a higher % of seeds.