TriadExpedition
Observer
I would choose one that you can touch up yourself, if needed.
If you rub a rock or tree, you wont want to pay a "professional" every time to touch it up.
Monstaliner is a DIY, as are others
6btex that is solid advice, however the project is so large in nature, it requires a professional to shoot the project, because It covers large areas. Basically it is like spraying a truck or car. Do not want it to look like I painted it with a rattle can.