Depends upon the nature of the care and the timescale.
My DH would find anything too close to nursing very very difficult. Although good at certain stuff, he's brilliant with my Mum's mobility issues, and already does loads of practical stuff around the house he is terribly squeamish and would be rubbish at anything involving blood, vomit, faeces etc.
My sister would be wonderful, she works in elderly care now and is great at changing dressings and stuff as well as basics. She's also good at relating to and communicating with people with dementia. I am sure that if she was young and healthy enough she would do as much as possible.
My parents are now too elderly to do much other than financial assistance occasional light respite or managing financial affairs etc.
I have no children and my sister only has one. I wouldn't want them to be lumbered although they are caring, practical and trusted.
My friends are similar ages and are dealing with elderly parents themselves, so they would probably be limited in what they can do.
I have decent insurance policies and assets. I would rather be put into paid care than have a member of my family or a friend step in to their own detriment.