The important qualities include armor class (AC), maximum movement (MM), hit dice (HD), number of attacks (AT), maximum damage (MD), morale (M), save (S), and special abilities (SA). The qualities were organized into two categories based on how important they were in combat mechanics. Values for each quality are written as a formula.
I’m still tweaking the formulas, but the end result is what I wanted; higher XP for low-HD creatures and lower for high-HD monsters and a system that accounts for more than specials and hit dice. I input the sums of each formula above into a single cell in my spreadsheet program. In this way, when I create an original monster, it is easy to create an XP value that is consistent within my world.