Other water-based media that you have a choice of, would be casein. Casein is a very old kind of paint and it's actually the binder for the casein, for the casein color is actually casein, a byproduct of milk. It sticks very well to things, it dries very opaque and it dries flat. If you need a stiffer color, than a water color, and you want it to be opaque and flat, then you need to go for the casein. Again, you can thin it down. If you thin it down too far, you will, again, interfere with how well it sticks to the surface. If you want it to last a long time, you need to pay attention to those things. Compared to that you have, of course, your acrylic, which is the basic. It is perhaps the most, I don't know if it's the most common media now. It was developed as an alternative to oil paint. You can wash it up with water, as long as you don't, if you leave your brush to dry, it will be plastic and you won't have a brush anymore. You can kind of start seeing the plasticity here in my drying palette. That will become just a layer of plastic, I'll be able to pull it off and I'll have a lovely pink splotch, in plastic. That's what some people don't like about acrylic but, what that means is, plastic is flexible so the acrylic will stay flexible, with time. You can roll up a canvas and it won't crack because the acrylic won't crack, it's plastic, it's flexible and it basically doesn't change over time. It doesn't go yellow and it doesn't oxidize. So, for a lot of people, acrylic is the paint of choice.
