We usually play three- or four-handed, and I will most often play Spirit. I enjoy it because the team can rely on you for solid questing while they do their other various things, and you have some powerful effects that can save the whole group when things look dire. I also enjoy playing theme decks and the heavily Spirit-dominated Rohan theme has some fun cards.
That said, I enjoy all the spheres.
That said, I enjoy all the spheres.