I do agree that upbringing and personality are very important - even though Skye is technically a rescue, she has never been outside a human home environment. I also suspect the fact that she lived with her siblings until 4 months makes her more tolerant of other cats, but also feisty enough to stand up for herself (but then, she's a tortie, so that might have something to do with it too!). She's very cuddly, but on her own terms, and isn't thrilled about being picked up or having her feet handled (but we will work on that).
Though Riley was a stray, he's more needy and human-oriented (at least with us - he's still very shy of other people). We can pick him up, cradle him, clip his nails, look in his mouth, the lot. He's not a lap cat, but will sit beside me, and he loves to be fussed and told what a good boy he is. He's generally quite relaxed, and is very vocal.
I'm sure a lot of their differences are down to personality and upbringing, but I have noticed that sometimes rescues are more human-oriented (my first cat was a rescue and was like this), while cats with a more "normal" upbringing are often affectionate, but on their terms. I just wonder if it stems from the fact that lots of rescues have had to rely on their humans to get their confidence in new, strange environments, while cats with a better start are more self-sufficient in terms of their confidence.