I have had cats all my life, both males and females, and always neutered. I think each cat is unique and the only clue you have is to observe the way they are when you're picking one, although it's not 100% reliable. Generally, if they're not happy to be picked up when young, they never will be terribly affectionate. The very most loving cat I ever had was a female, and when the shelter worker put her in my hands as a small kitten she curled up and purred immediately. I have had very friendly males, too, but that little tortie was the sweetest, and I'll always miss her. If you want affection, shy away from a cat that was not handled lovingly by people during the first weeks of its life. Any cat can be friendly, but the odds are against it if they didn't learn early that people are nice.
Brushing a cat regularly seems to make them more affectionate. Maybe it reminds them of their mom's grooming when they were tiny. It's good for them, whether it works for that or not.