Students and parents often ask how important extra-curricular activities are to college applications and which activities are the "best?" There is no such thing as a "best" activity, what truly matters is what the student enjoys best.
One of my first recommendations to students is to participate in those clubs and activities that interest them most and do not think about college applications. Students should never choose a club or team because they think it will "look good" in the eyes of college admissions officers.
Quality Not Quantity
What colleges are looking for are students who spend their free time constructively and feel a commitment to one, two or three activities. Admissions officers don't count the number of activities, rather they weigh the commitment and consistency of them. Admissions committees are looking for a sense of who the student is as a person and what talents, interests and skills he/she will bring to their campus.
That said, colleges understand that a student's interests can shift throughout the four years of high school. A student shouldn't continue an activity he/she has lost interest in. The athlete who played soccer in freshman and sophomore year, but drops it in junior year in order to be serve on student government will not lose any points. The student who drops activities without adding something else, may. Put simply, it's not so much what you do, but how you do it.
Academics Still Matter Most
Last, but not least, remember that extra-curriculars - no matter how impressive - never make up for grades, course selection and test scores. These are still the top factors admissions committees consider. A solid student resume reflecting activities and possibly leadership positions, can certainly enhance an application, but it cannot substitute for academic performance.