Define “best” before comparing
In a creature sandbox, “best monster” could mean the fastest movement, the strongest visible attack, the cheapest useful build, the rarest look or the easiest creature to control. Those are different questions. Do not merge them into one tier label.
01Build recordSave the visible parts, traits, name and any shown cost.
02Same testUse the same area, mode and starting condition for every creature.
03One changeChange one part or trait so the result has a clear cause.
04RepeatabilityRun the comparison again before calling a build fastest, strongest or best.
Until Monster Maker exposes a repeatable stat or challenge surface, the honest answer is a comparison method rather than a fabricated S-tier list. Use the beginner route to capture the editor fields first.