I was just thinking about this the other day, for some reason and I decided that if I could give anything at all to the people I love, it would be the ability to see themselves through someone else's eyes.
Sounds mad, but think about it: sometimes I look at my friends, or my little brother, and I think to myself that I love them so much and to me they are indescribably special that to try and verbalise how I feel about them is just depressingly inadequate. My little brother especially - sometimes he gets so doubtful about himself and his own abilities and talents, etc. and I think that if I could let him have a glimpse of himself through my eyes he's never doubt himself again
So that's what I'd give them. Possibly there are better ideas, but I'd be interested to hear what other people would give the ones they love in my hypothetical magic world