A little honest perspective from the 6.5 yr old.
Why do you love grandpa so much?
M: Because he teaches me lots of fun things and he tells a lot of jokes and funny stories that make us laugh.
Why do you love grandma so much?
M: Because she plays with us and cuddles us a lot.
Why do you love mummy so much?
M: Because she looks after me and I know she loves me a lot.
Why do you love daddy so much?
M: Because he gives us a lot of yummy treats, those that Mummy said we can't have. And he buys us a lot of toys.