All anecdotal, but I've had numerous cats and currently have 5 (two adults and three kittens.) All are spayed/neutered. I would say all of the male cats I've had/currently have are more affectionate, on the whole, than the female cats I've had/currently have.
My two adult female cats (one deceased, one currently 9yo) were/are affectionate enough, but on THEIR terms. They'd come by for a bit of a snuggle or a few scritches and then they'd be off to do their own thing. My 9yo girl won't protest if you pick her up, pet her, snuggle her, etc. but it's rare for her to jump up onto your lap and be the one to initiate contact.
As a comparison, my adult male cat will yell at you and leap onto you if you are not giving him attention. He wants to be in your face (in an affectionate manner) or laying on top of you in some way at all times. He wants to know what you're doing at all times (and wants to be included in it.) He has a sense of primitive scheduling, knows when bedtime is "supposed" to be, and gets very loud when routines aren't followed to his satisfaction! He's definitely way more "involved" in being a member of the family than my current adult female cat or my previous adult female cat (if that makes sense).
All of my kittens are pretty affectionate - I've got two 7-month-olds that are siblings (boy and girl) and a 6-month-old that is a singleton (boy.) However, the girl kitten is very much a diva and demanding of attention and affection, whereas both boy kittens are much more laid back and will happily snuggle you and purr away for hours. I've sat and watched hour-long videos with the 6-month-old purring away on my lap.
6-month-old kitten is also best friends with my Belgian Malinois, even though the dog is 8 times heavier than he is!
tl;dr I've always personally found my female cats a bit more standoffish and independent, and my male cats more affectionate and involved.