Highest rating armour

It is absolutely worth it to craft one of the Witcher sets of armor, either the feline, griffin or ursine armor. Those are pretty much the best armor for their level and can be upgraded three times. You can buy maps that will lead you to plans for witcher armor at various merchants.

Other armor pieces are probably not worth it unless they're a significant upgrade and you have the materials available. Buying materials can get extremely expensive very quickly, but you can find almost everything lying around somewhere.

The Griffin armor is a medium armor set that requires level 8, if you want to craft something now I'd suggest you try to find it. The feline/cat armor is level 14, and the bear/ursine is level 17.

The weight of your armour affects the rate at which your stamina regenerates.

So heavier armour, despite providing more damage resistance will prevent you using signs as frequently. Wearing lighter armour will not penalise your stamina regeneration, so you can use more signs.