My grey loves her dice bell toy. She has had it for very long time. She also loves foot toys, and musical toys
My Quaker on the other hand loves only one toy really, its his shiny basic bell toy, looks kind of boring, some reason she loves that thing, and never likes parting with it.
Toys you might want to try are musical, things help with forging, and I know 8 beaks has really good toys, all kinds as well.
There is also educational toys out there, if you are willing to shop online there are so many to choice from.
I know my grey loves things that are bright colored, can be shredded, or can be throw around.