When to Use Which Method
EnviroTex alone is great for still water simulation, and you merely need to be obsessive about mixing exactly as directed in order to get good results. (Getting exactly equal parts of resin and hardener into the mix and scraping the sides and bottom of the mixing container with the flat stirring stick are the key factors here.) Don't forget to use either human breath or a propane torch in order to pop the bubbles that come to the surface. The directions say limit pours to 1/8" thick, but I've done up to ˝" pours with no problems. If you pour too thick, the bubbles won't be able to rise to the surface. This is one of the methods that is catching on fast in the modeling community, according to recent layout tours I've been on. Use EnviroTex for still water and in combination with acrylic gloss medium liquid or gel for moving water like streams, rivers or waterfalls, or to simulate sea/lake/pond water with waves. But I have some reservations about the moving water issue, as you'll see later.
For quick, easy, cheap water with waves, when you're willing to settle for less than optimal simulation because of the speed, ease and cost, use a textured acrylic shower door (which is cheap only if you get a used, broken, or discarded one) or ceiling tile plastic that looks a lot like gentle waves. You don't have to do much more than cut it to shape, install it over a properly painted surface, and plaster in—and scenic—the shore lines.
If you don't mind the bother of lots of coats, acrylic gloss medium alone is fine. It allows you to avoid the mixing and bubbling hassles that come with EnviroTex or the mixing hassles and stinking problems you get with casting resin. And nothing beats acrylic gloss medium for surface feature creation.
If casting resin's tendency to form ripples as it sets up seems really attractive because you don't want to brave creating your own ripples, you may want to ignore the stench and try it. I got nice results from it in the 70s, but I must admit that the memory of the fumes will keep me from using it again.
I wouldn't recommend real water or gloss paint alone, or the simulated lake and pond "film" available from a few sources (unless you have a quickie, temporary application). I did a working waterwheel with real water in the 70s, and it was a novelty that got old fast—the water ran too fast for a scaled down model of running water. Gloss paint and "films" are not convincing compared to other water simulations.
By the way, in spite of many articles that have spelled EnviroTex with a hyphen in the middle, the correct spelling is EnviroTex.
Tip: In E-Z Water use, never use an enamel-lined can (like an organic vegetable juice container) for the heating container (no way I'm telling you how I know this!) and always lay track, bridges and plastic structures after all E-Z Water modeling is done. And make sure bridges near water are removable in case you need to repair scratched water in the future (which requires a heat gun, which is very hot).