My personal preference is Y up, X right, Z forward (all positive). I believe this is Unity's?
Freya Holmér (@FreyaHolmer) on X
ok here's my ultimate answer to Y vs Z up: step 1: imagine a 2D world map for your game step 2: that's your XY plane! step 3: decide what "up" means (usually the opposite direction of gravity) step 4: see which axis "up" points along, which is usually Z or Y
