LinkedIn is currently the best performing for organic traffic. If one person likes a piece of content then all of their connections see it. Pinterest is designed for shopping in mind. You'll notice even shopify has pinterest share enabled as default. Reddit has great communities that are always looking to be the first to try/discover anything. Since you already have share on FB, Twitter, etc. enabled, it should be easy to implement. We can then decide which one we want to activate for our store.