In terms of emotional reward it really depends on the cat, I have two, a boy who is about 17lbs (not fat just big) and a little girl who is maybe 7lbs, the boy

In terms of emotional reward it really depends on the cat, I have two, a boy who is about 17lbs (not fat just big) and a little girl who is maybe 7lbs, the boy just does his thing with the occasional headbutting on the way past but the girl, she just wants to sit on my knee all the time, she'll snuggle up across my shoulders and go to sleep (and stay there when I get up for tea), when I'm at home her purr is my constant companion. We got them really young (rescues) and she just bonded to me from the start :).