Solo. Don't have to deal with other peoples time/schedule/lag/problems. Better EXP too.
If you are lazy and want to quad, I'm sure Dreadlands is decent at that level.
If you are semi-lazy and want to charm kill, Overthere has some animals at that level.
If you are a boss and want to charm kill, Kedge Keep is the best EXP you will find at that level once you figure it out.
EDIT: Future note, use the
Priests Subsection for future druid related questions.