I've had a long list of what I want sitting in my head for years...and I keep adding to it as new morphs are produced. But right now, I go by reaction. If I come across an animal that makes me instantly feel "I have to have it" and makes me desperate to find any way to get it...that's how I know I truly want it and it's "The One". I felt that way about all of my snakes and feel that way about a pastel I'm eyeballing right now. I won't spend the money unless I get that feeling and am absolutely sure it has all the qualities I want.