When I go toy shopping, I bring Salty with me (in harness), and let him pick out the toys. At this point I kinda know the types he prefers, so its not really necessary, but it is fun. I suggest that you try a few different types and let Aristotle choose. The ones in tatters on the floor of the cage are the ones to buy, LOL.
Small parrots usually like small scale toys - a toy for a macaw or Amazon, Grey or cockatoo would likely be untouched by a Green Cheek Conure. Small scale toys are not easy to find, most are for budgies, which I think are too flimsy for a conure.
Be aware of toys that have small bells on them, the clappers are easily removed by parrots who are determined. I remove them. Also be aware of toys that include rubber (like those miniature sneakers) or other easily destroyed plastics, there is a chance they will ingest fragments of them. I try to stick with toys made from natural materials when possible. Fortunately, Salty agrees with that!