I've never thought about it too much before but there are so many things that I could say are my favourite from outside the house to inside & material to immaterial. In the end I settled for a tiny 2 inch book that I bought when I was a child (& cost 29p!) and my ornamental oversized glass perfume bottle which catches the light beautifully. The book has a poem in it called The Legend of the Raindrop which I have always loved reading. The pages are now very worn and brittle so I must preserve it a bit more carefully from now on.