I use Roudybush pellets for both my Parrotlet and my Pineapple GC Conure. The bird shop where I get all my supplies weans all their babies to Roudybush. My avian vet said Roudybush or Harrison's are the best.
The only difference in the Roudybush pellets is the size.. The Parrotlet eats the "mini" size. When I brought Libby home (the Conure), the bird shop gave me mini and medium for her. She kicks them out of her dish immediately, won't eat them! I put them in a baggie and smash them with my meat tenderizer hammer and she gobbles them down! She's a much bigger bird than the Parrotlet, so should be able to eat the larger size, but NO WAY! The next time I buy them for her, I'll get the "crumbles" version -- will be much easier!
They all have their likes and dislikes, I guess! I'll tell you one thing -- ALL three of my dogs love the pellets that fly out of the cage, no matter what size! LOL!