I agree with the PP who suggested trying a bunch of different sports in the early years and have them learn some skills before putting them on a team. For boys, having a working knowledge of basketball, football, baseball, and soccer will be good social currency when they get to school - they don't have to be scholarship material, but I think it's good to at least know the basics of each. Every kid should know how to throw/catch/kick a ball. And of course swimming is a life skill that every kid should learn from an early age - again, not to win meets, but to not drown and to be able to hang out at the pool with friends when they get older. Bike riding is the same. I think kids need to learn to be active from an early age.
And while I get that some kids aren't naturally athletic, I think exposing them to sports early on helps them get comfortable with their bodies and build basic motor skills. I thought gymnastics was also great for building balance, strength, coordination, etc. My kids stopped taking classes when they were in elementary school to focus on other sports, but the skills they learned in gymnastics have continued to serve them well in all sorts of ways. Also, taking sports classes teaches them how to follow directions, be part of a team, work with other kids, etc.