Every chef has a different answer for this one. Some prefer the purity of eggs by themselves, just whisked and scrambled. Others use water to make it fluffy as the idea being that the water steams during cooking and makes it fluffy. Others like to use milk or ½ and ½ or heavy cream to make the eggs taste creamy and rich. However you like your eggs, it doesn’t matter as they all have their benefits.
Scrambling just the eggs gives you an eggy taste that really allows you to have a different mouth feel than a hard fried egg and still lets you eat it like a regular egg.
Water makes the eggs fluffy, but too much and they are really too runny. The nice thing is that this is a simple way to also stretch the eggs you have to feed another.
Cream or milk gives the eggs a luxurious taste and mouth feel as it makes the eggs creamy without taking away from the egg flavor that you expect.
If you have time, try to make a single scrambled egg using each method and see if there is one that you prefer. Once you have your preferred method you can then add herbs or a little cheese to make it richer or just change it up completely.
Regardless, just have fun trying out new types of liquids you can scramble with.