Sure Syd's whimsical and carefree and upbeat songs are awesome, and I love them a lot
But, For me, it's all about Roger. Roger's lyrics, and his voice are both just so amazing. His voice just works so well with his lyrics, because both carry so much emotion within them! So many people can relate to Roger's lyrics in so many ways.
So it's definitely Mr. Waters, with Syd as a second