Yes! I have a sun AND a nanday.
They are both very different, and both have a few stereotypical attitudes and quirks I've found a lot of suns and nandays share.
My sun conure is a year and a half old, she's a real sweet heart (most days) but is also very bossy, nippy and completely no-touchy. When she was a baby, she was a typical young sun conure - cuddly, friendly, silly. But as she turned about 7months~12months she became more aggressive and is very hands off. She loves to sit with you and just be in your company, groom you etc - but if you try to pet her she'll scream at you and maybe even give you a warning bite. She steps up easily and all of that, but doesn't want to be petted at all. Sun Conures are mainly known for being bossy, playful, friendly, nippy, dominant and cuddly. Lola is most of these things, except cuddly. I know a few people with sunnies like her, but
MAJORITY of sun conures do love cuddles and lots of attention.
My nanday is completely different, she is a clumsy, silly, cuddly snugglebug who just wants to be literally cuddled like a puppy constantly. She is the sweetest little thing and secretly my favourite. She is slightly bigger then Lola and looks kinda chubby. She is probably the best bird I've ever owned. She is a MASSIVE drama queen, however. She will have days when she chucks huge tantrums and is a big grumpy bum. Especially after baths, she LOVES water and bathing, but as soon as she's finished and is all wet, she gets incredibly grumpy and irritable and you can't even look at her or she'll scream at you and go to bite you, lol. She's only grumpy while she's wet though, so only for an hour or two, then she gets completely over it. As long as you don't pay her any attention after a bath, she's fine. lol. Nandays in general and very known for being huge drama queens, but also very sweet, cuddly and affectionate.
They are both very, very different. But they share one common trait, they are very loud. Now, I would not compare them to a cockatoo or macaw, however, they have a very high pitched screech. Some people just cannot handle it. I personally don't find it that bad, but some people think it's the worst noise in the world. I would suggest visiting breeders and suns/nandays in person as youtube videos and sound files do not do their sound justice. If you live with more then 1 person, then take them with you. It's a hard noise for some people to put up with... but I don't think it's that bad. I've heard lorikeets, greencheeks, princess parrots, ekkies, african greys, ringnecks and alexandrines make high pitched noises that sound identical, so I think suns and nandays are given a bad reputation over their "screaming" but it's really...
not that bad. My two only scream for a few minutes when we get home from work, and when we get up in the morning. They don't make a peep while we're not home, and when we are home during the day, they might scream maybe 1~3 times, if at all. If they are on your shoulder when they scream, yes, your ear will ring for a second! I'm not saying they aren't loud, but they aren't as bad as people make them out to be. I've found that a lot of suns and nandays have different sounding screams, too. Luckily, my two don't have obnoxious sounding ones. People also say nandays are louder, however my sun is slightly louder then my nanday.
Both my birds are friendly, but they are not good with strangers as they get scared and go quiet. They are bonded to me as well as each other, but still like to be with my mum. In my opinion, nandays are awesome birds and I would suggested/pick on over a sun anyday, but it really depends on the individual bird. Probably like 80% of suns are cuddly little love machines, but then you get ones like Lola, as well. So it really depends. There are general stereotypes they share but most of the time, it's the individual bird's personality.
Feel free to ask my any questions I missed!