I have a pair, male and female brother and sister.
The boy is a bit more distant than the female. Will come up and lick me etc, but won't ever lie on my lap to be stroked. He will also only let you stroke his head on passing for a maximum of 5 seconds before wandering off.
However, he is very protective of dd. When she was sick recently, and woke up during the night crying, he (kitten boy) ran in and sat with her for four consecutive nights.
The female kitten is much more affectionate. She will sit on your lap for a long time, love being touched, will nudge your hand if you're not stroking her, will fall asleep on you etc. But she is very timid. As soon as the buzzer goes or door opens, she shoots off. She hates visitors coming in. In fact, none of my friends/family have even seen her because she hides when they visit.
I've had no problems with spraying etc because the boy was neutered at 4 months old.
I can't tell that either of them are messy. they play with each other, and i've had no destruction to any furniture etc.
I love them both! No idea if a boy or girl would be best. Just get the two.