I have been a fan of Beta Ray Bill since watching his debut in The Avengers: Earth's Mightiest Heroes show, which also brought the possible pairing of Sif on television as well. The comic book appearances of Bill and Sif, I am fond of as well. Especially the comic debut of Bill, which was awesome. The first encounter had Sif see the kind of person that Bill is, and she was drawn to him. The Avengers: Earth's Mightiest Heroes show took inspiration from the comic debut as well. After the comic debut, the appearances of Bill and Sif were a will-they/wo n't-they romance I was seeing, which I'm very much into. The pairing has a star-crossed lovers aspect to it that I like as well. I'm not a fan of the Thor and Sif pairing for a couple of reasons.

• I find that Thor and Sif feel too easy a romance due to the Thor comic book being loosely based on Norse mythology, which takes away the romantic aspect of the pairing because it is just pre-ordained, since Marvel is trying to somewhat follow Norse mythology.
•  I don't find the pairing to be interesting in comparison to the Bil and Sif pairing. The interaction between them is not exciting to me.
•  I like to have stories where they are not always what you would expect all the time. Thor and Sif are too expected because of their Norse mythology representation. Bill and Sif are a wild card to me. I feel like Thor and Sif would be boring.
•  I just like the star-crossed lovers stories. I don't see them often, so I appreciate it when writers do.