The simple answer is both and in equal measure. This is because they both do completely different things.
Polish is an abrasive that you use to get rid of small scratches, swirl marks, and other small defects. Polish does this by removing the top layer of your paintwork.
This makes the depth of the scratches less pronounced in comparison to the rest of the paint. As a result, you will get a cleaner reflection, instead of the hazy reflection you get when there are more defects in your paint.
So, polish is great for removing defects from your paintwork. But it doesn’t protect very well, and this is where wax comes in.
Wax acts to leave a layer of protection on your paint. This serves to protect from contaminants like rain, dust, insects, bird droppings – anything that would otherwise risk your paintwork becoming damages again.
Wax is typically made from carnauba, which is a natural brazil wax, although there are also good synthetic versions out.
The good thing about this type of wax is that it has a very high melting point, which helps it to keep protecting your paint in hot sunny weather. It’s also waterproof, making it great to protect from rain.
While these can be used on separate occasions, it is advised to use both if you want to get the best finish. If your car has no imperfections, e.g. recently polished, then you can just apply the wax.