Archery and Shadowplay are essential, and have everything you need for a traditional Ranger type class. The third choice, well, you can vary that depending the needs of the moment. For mobility there is Auromancy, but you may want to experiment with other options depending on what you're doing. With Auro, that'd make you a Primeval. I know Ebonsong is really good too, but I'm not sure what it's third skill tree is.
Swapping classes is super easy in this game. There is also a built in ability to have three saved builds if you purchase an item to unlock each slot.