I'm surprised that (at least for now) Remus is chosen as the better gift-giver. That was one of the easiest questions for me. Sirius is so caring about those he loves, I'm sure he won't rest until he finds the most perfect gift for Remus each and every christmas/birthday/anniversary.... I also can see him just giving Remus little gifts that would melt his heart without any reason what so ever, just cause he was walking in the street and he saw something and just HAD to get it cause it would be perfect for Remus and he would love it.