Stannis Baratheon on Game of Thrones

Now let me start by saying I have nothing against Stephen Dilanes performance as Stannis on GoT he is a great actor. I just always felt that he didn't look anything like Robert or Renly on the show and find it hard to believe they are all brothers. I think John Rhys-Davies would have been a perfect Stannis. He has the look, the acting talent, and the sort of commanding presence that Stannis has. I know it didn't show that much in LoTR but I have seen him other roles were he played a king. That being said I do love GoT I just think there is just this casting choice I would have preferred. Any thoughts?