The first sentence is fine. It tells us that both of your parents are wonderful.
If you want to address the issue of non-traditional families, you could say that both of your Moms or Dads are wonderful. If you have more than two parents, you'd better spell it out clearly because two is the total most of us start out with.
A favorite is the one thing you prefer above all others, so it is correct to use the singular. It's fine to name more than one favorite. In that case you would say, "A and B are my favorite sports."