Why is acrylic the best paint for beginners? Because it's so versatile and simple to use, especially because it's water-based. You don't have to mess with linseed oil or paint thinners.
It's also easy to mix and render with acrylics, versus water colors, which can be fickle, and oils, which you really need to use for awhile to learn the consistencies and techniques associated with heavier paint. Also, acrylic is fast-drying.