Think of a sealant as a synthetic wax. They both do essentially the same thing, protect and beautify the paint, but they do it different ways. In general, a sealant will last longer than a wax. But a wax will give a more wet, deeper appearance to the paint. Quite a few people will add a coat of a natural wax on top of their sealant.
Unfortunately, there's really no one-product-fits-all product out there. Different people like the way different products work, and products will look differently on various colors of paint. Browse around a little and find one or two that interest you (maybe looking at pictures will help a little) and try em out.