What are the best things to craft in The Witcher 2?

First off, there's no point to crafting for the purpose of selling. You'll make no profit that way, and you're better off just selling the components directly. In many cases, you'll have to buy bits of stuff to craft, and the charge for this is so high that it puts you firmly in the red.

Armor

Geralt is a bit of a glass cannon, so honestly most of his armor options give such a small boost that they aren't worth crafting/buying. Your chest armor is going to give you most of your defensive improvements, and your secondary armor bits' stats won't change much throughout the adventure. For instance, you might get +30 defense from your chest armor, and +2 from your boots, if you're lucky.

From the start, you should have the Blue Stripes Combat Jacket (since all PC users got the EE upgrade, and the EE is the only console version available...) which will probably last you until you can craft Kayran Carapace Armor. You might find a bit of useful armor occasionally from here out, but the piece you're really shooting for is Vran Armor which must be crafted, but is also the end result of a long and drawn out quest, which you've got to start early and carry through each chapter.

As far as the other bits of armor go, there's not a lot to really recommend. Just equip whatever's available, and if you see something that's a significant improvement, consider crafting or buying it, but the gains from these bits are typically laughably small. For instance, the base armor of boots never gets above 2 at any point during the first playthrough of the game.

Weapons

Again, some long quest lines and/or careful ingredient hoarding will reward you in Act 3 with a pair of powerful swords - Zerrikanterment and Caerme, which both must be crafted.

In the meantime, you can craft some interesting Meteorite swords, although expect to pay out the nose for these. I seem to remember in the Enhanced Edition that I found a plan in Act 2 which I was able to craft, and which gave me a large boost to my damage, but it might have been a glitch - it was called Marag Bator.