Personality-wise, Sun and Jenday conures are virtually identical IMO. They are species whose genetics are so close, that they easily and readily hybridize. The biggest difference is color. There are subtle differences, but the personality characteristics are going to hold true for pretty much all species of aratinga conures.
Aratingas are a great size (not too big or too little), and they tend not to be aggressive around other birds. I have a book that describes suns as "stunning plumage, extraordinary disposition, and exceptional quality in a companion," and I completely agree. They are smart and energetic- which makes them great trick birds. They're more forgiving then a lot of other species. If you make one mistake you haven't ruined your relationship with your aratinga forever (which might not be true for, say, a cockatoo or an amazon). They are (in general) very affectionate, cuddly, hands on birds. They're clownish and silly in a completely endearing way. They are very charismatic and just completely charming. I think they have the best most loving, playful, wonderful personality of all parrots. I would never be without one.
On the down side- they are LOUD. Ear splittingly LOUD. If one is on your shoulder and happens to sound off, it's like a bullet to your brain. I am fairly certain that I have some permanent hearing damage from them shrieking directly in to my ear like that (and i don't mean that as a joking exaggeration, I mean it literally). Their vocalizations are horrible in volume, quantity, and quality. The don't have a cute little twitter or a whistle. The most common sound the make is an extremely shrill EEK EEK that you can feel reverberate in the roots of your teeth. A lot of species of birds vocalize frequently (like budgies or lovebirds). They keep up a pretty constant, never ending stream of chatter. But they aren't loud. Other species of birds (like macaws) have a lot of volume, but don't tend to vocalize often beyond the standard morning and evening calls that nearly all birds make. Aratinga conures have both issues- they vocalize frequently and with an absurd amount of volume (with a bonus of their call being unpleasant). Watch all the you tube videos you can of aratingas screaming- be sure to turn your speakers all the way up! But even that won't do it justice to what it sounds like in person.
Pyrrhura conures (like Green Cheeks) have a reputation for being quiet. But I completely disagree. I think they are QUIETER then their aratinga cousins. But that's sort of like saying a bullhorn is quieter then a chain saw. Pyrrhuras also tend to be less cuddly and more nippy then aratingas.
IMO, there is no parrot that has a better personality then an aratinga conure (and I'm especially partial to suns because of their exceptional beauty). They are cuddly and playful- they are just the whole package personality wise. BUT if you (or anyone in your household) is sensitive to noise- an aratinga IS NOT for you. And, truthfully, a pyrrhura probably isn't either.
The number 1 reason conures are rehomed is because their owners couldn't take the noise. But you decide the noise won't bother you and you get a conure. And it doesn't bother you- hurray! A perfect match! But hold on there- when acquiring one, please keep in mind that they live for 30 years. If the noise doesn't bother you NOW, what about 10 years from now when you, for example, decide to start a family. Does it bother you now that you have a baby in the house who's trying to nap?
I don't mean to sound overly negative about conures. I ADORE my sun. There is, truly, nothing about her personality that I would change. I love her more then life itself. I would run in to a burning building to save her. But way too many are dumped because people get them thinking that THEIR bird won't be a noisy one, or that the noise won't really bother them that much. And then it does. And the birds suffer for it. Please, if you have the least bit of sensitivity to noise, don't get a conure.