Diaper Size

Hello!
I have a lot of diapers already in different sizes, but I decided to go and buy a lot more today. At 32 weeks, my little girl weighed 3 pounds 10 ounces. What size do you think I should stock up the most on?
My sister said with her boys she mainly used size 2's with them. Online, lots of people surveyed that they used 3's the most. At her rate, what do you all think?