I would definitely avoid inbreeding whenever possible. While we aren't seeing many problems now, we don't know what will happen 10-20 years from now. Also, what if you breed siblings and then someone buys a 1.1 pair from you? Are goblins that much more special than regular YBs? Because there is a huge selection of YBs, and many of them are probably from normal x yb breedings. Get the two from different clutches, and you'll be less likely to run into problems in the long term.

As far as making up your mind, decide what you like best in every morph you can't decide between. Go with the first snake you see that matches the vision in your head.