I am looking to grow some herbs for medical remedies. I only have a few pots to start with. I am already growing parsley, rosemary, basil, garlic, ginger and chives. They are all growing well. I am in zone 10. My question is: if could only grow 2-4 more herbs which ones should I choose?

make sure they are legal herbs! The road to hell is paved with good intentions! I know first hand!

Echinacea is a useful herb and also very beautiful. You may also know it as purple coneflower.
I'm also fond of comfrey - it has many uses but it can also spread easily. Not sure if it would like growing in a pot.