Acrylic paint is a good choice because it adheres well to a well-prepared surface, can withstand weather if varnished properly, dries quickly and can be cleaned up easily with water. Liquitex Soft Body Acrylic is often used/recommended for murals as it provides good coverage and levelling.
Golden is another range of acrylic which is highly recommended for mural painting. If you are painting flat, without texture you will probably want to use their creamy Fluid range.
The most important aspect for a long-lasting mural is sealing it to protect it from the weather conditions and sunlight. Golden do a varnish which has UVLS (Ultra Violet Light Stabilizers) and provides a very durable finish. It's a Mineral
Spirit Acrylic Varnish and is recommended for interior and exterior use.
Here is a really useful article which looks at mural painting and also describes how to use the MSA Varnish most effectively to get more protection from the elements.