Milk or water for fluffier scrambled eggs?
If you want slops use the Ramsay method. If you want something with texture and taste try this

Turn the heat onto max and use a light weight pan for gas, or a medium weight pan for electric. Add a small drizzle of oil to the pan

In a strong deep bowl add a splash of milk or water and two eggs (say 20% liquid to 80% egg) 

Beat like crazy for 20 seconds (use a whisk or a fork)

When the pan is sizzling pour in the egg mixture and use a medium spatula (a 5cm wide strip of wood is great) fold in the cooked parts as they appear. Work quickly

It will begin to form a loose lump in the pan. Keep folding the egg into the lump until all the liquid egg is gone

Optionally add a handful of coarse chopped broad leaf parsley or some thinly sliced cheese just before the final few folds

The cooking phase should have taken seconds, not minutes

Remove pan from heat

Let it rest for a while before moving so the egg has time to set

The texture is changed from smooth to rough by how often and hard you fold the egg