Oh man, I can't tolerate Jendays. They are loud, loud, loud!!! I would say just as loud as Suns. Same with the Nandays.
Green Cheeks, like most Conures, are very energetic and very playful. Chi Chi is constantly hanging off of some part of her cage. Or laying on the bottom on her back (she scared me to pieces the first time I saw her do that!).
She can say about 5 or six words...Hi baby, Night Night, Good Bird, I love you (okay, that's more like 4 phrases and 7 or 8 words...lol). She is really clear, but quiet.
She has a high pitched squawk (not as loud as the Aratinga Conures), but uses it rarely. And they are smaller then the Aratingas too. She weighs in at about 47 grams (give or take).
Here is a pic of her: