Chris Hadfield responded to this question this way:
The Soyuz is very small and the weight balance affects how it flies,
so we are very restricted in what we can bring. I thus chose small
items for my family and close friends: a new wedding ring for my wife,
commemorative jewellery, a watch for my daughter (I flew a watch each
for my sons on previous flights), a full family photo for my Mom and
Dad, and some mission emblem guitar picks.
The video below mentions some of the items two astronauts listed - Scott Kelly mentioned 'a little tool pouch... certain kinds of sweat shirts and sweat pants... certain kinds of shoes for the weight-lifting device" Reid Wiseman said "I'd make sure I had some local baseball, local football shirts", he showed a toy giraffe and said "I got two kids, and so this one actually flew with me in space, this is giraffity", also "here is my yo-yo, that I had up there". He showed some of his kids' drawings that he had.
The food he showed likely didn't count as personal luggage, but as 'bonus foods'. Each astronaut has a supply provided, as a personal comfort, which is helpful for morale. They come up with the care packages shown later in the video.
Sunita Williams had these items
The Indian American is busy packing up her personal things which she
took up with her, including a yo yo, a crew notebook with pictures,
speciality t-shirts and a family photo album.
Yes, each person is allowed five kilograms of personal items,
including clothes. I took a few personal items from people close to me
so I could return those to them from space: wedding rings, little
pieces of jewellery.