Shelagh Fraser and Mark Hamill shared a close enough resemblance that it’s easy to buy their characters as biologically related. Beru also seems to regard Anakin’s memory with more warmth and happiness than Owen ever demonstrates. Those are the reasons why I think Beru makes for the better Skywalker sibling.

I like Owen better as Ben’s brother. Resentment/jealousy over Ben leaving the farm to become a Jedi — along with Ben’s botched training of Anakin, especially if Owen and Anakin were best friends — go a long way towards explaining Owen’s antagonist with Ben and his overprotectiveness of Luke.