Real is always best if you have the choice in anything isn’t it? There are a lot of simple tricks such as using a broad range of rock and pebble sizes, local weathered rock, shape, plantings and placement. Also when building it takes an eye that can see how the water will fall from or move around a rock or trunk and this gives the effect. You often see waterfalls built where a lot of effort has gone into making the rock look good when it actually disappears when the water runs over -its not common in nature to see a perfectly flat flag stone stacked up for example. I often go walks up creeks to understand better how they work and flow. Simple things such as how water changes course due to an object or large rock – that’s how we get such differing effects in a water course and will depend on the type of creek you are building. There are the gushing mountain creeks that step side to side in beautiful choreographed chaos and then there are the gentle sandy meandering streams and everything in between.
A bowl shaped straight construction covered with say 40 mm pebble looks more like something you find as a roadside drainage system than a creek but I come across them all the time when we do retrofits and redesigns for clients. Also if the space allows a stream with various small cascades that twists and changes direction often holds more impact than one high sheet of falling water.