You can't go wrong with Blue Velvet if you own a dark colored car. Infused with a high percentage of carnauba and blue in color it is made for that dark colors. They will be shiney and protected but even on lighter colors it will not do any harm.
Being a dark wax, you can see where it's gone... and if you apply no more than two layers it isn't going to dramatically alter the original appearance. But beware of Blue Velvet's seductive dark side - it may stain application pads and buffing cloths.