I have had both Bourkes and Scarlet Chesteds. They are nice easy pet birds, that don't make too much noise. As someone mentioned, they are not cuddly birds that like to be touched or scratched. But if hand-raised, they can become very friendly and bond with you.
My Bourkes call me when I come home and want to come out. They will fly right over to me and sit on my arm or shoulder. And they will stay with me for hours if I let them. But they are pretty calm - don't make much noise - they will be happy to either just sit there or nibble my face. They do not bite. They also like it when I lay on the floor with them - they like walking around on the floor and will stay by me when I am down there with them. But if you want a real interactive "hands-on" type bird like a Conure, that you can pet and hang upside down etc, you may find Bourkes a little boring. They don't like being petted and you will probably scare them if you try. As someone mentioned, Bourkes do not climb easily like other parrots so it is best not to clip their wings, as they are defenseless and can run pretty fast anyway - you need to tame them with gentleness and slow movements - you can't really "force" them to be tame like some other parrots. However, an initial wing-clip when you first get your Bourke may help in taming. Even after they are technically finger tame, however, it can take a little while for them to bond to you (i.e. to "like" you) - so you need to work with them gently every day until you get there. But once tame, they are very nice friendly birds.
Scarlet Chesteds are a little trickier and more wild by nature. They seem to be less domesticated than Bourkes and harder to tame. They seem to have more of a response to "flee" than "freeze", which Bourkes tend to do. I have had 3 of them - all hand-raised - but I'd say only 1 ever became as tame as my Bourkes and even then it took longer. My other 2 became more wild and would not sit on my finger or arm very often, though I could let them fly around my house and they would return to their cages, eventually! And when wing-clipped, they still try to fly and end of crashing a lot, possibly hurting themselves. So if tame pets are what you want, I would recommend Bourkes over Scarlet Chesteds.
Bourkes and Scarlet Chested Parakeets are very compatible and can be kept together, in the same cage, at least when not breeding. They are related but they cannot interbreed. But I would still separate them, into 1 pair per enclosure, if trying to breed either species.
Here are some photos or mine, past and present. This is my Bourke named Twitter. I have had her for 5 years.
She loves to fly around my house and also likes to bathe, when she gets the chance.
This is the only Scarlet Chested I had that ever got really tame. It took a while but eventually we got there. Unfortunately, he died of Pro-ventricular Dilation Disease.