It’s going to taste the best fresh especially if you are going to make tea or use it in cooking, but you will need more of it to get all of the benefits, which can make it strong and overpowering for some people.
You can also use a tincture form, which will be more concentrated; or an essential oil form, but you have to make sure that the brand of essential oil you are using can be ingested. Then you can use less and get more of the properties of the ginger.
I personally don’t like using ginger powder unless I am cooking a meal with it and trying to save time. The flavor is a little different in the same way that all spices taste a little different dried and ground and it is better to use fresh sources whenever possible.
So if I was going to make tea, I would use fresh ginger. Personally, I don’t even mind the ginger pulp, but you can also strain this out. If I just want to supplement, I would use a tincture or an essential oil.
i mash up the root (fresh, always) and throw it into a cup of warm water and drink it. sometimes ill chew the root and eat it that way. i dont think many can handle it that, but i like to go full strength on everything.
you can put it in a garlic press and crush it that way.
Be carefull with tea's from brands like twinnings, they are full of pesticides and low grade ingredients. I can recommend Numi tea, it's fully organic with no added adetives or artificial flavours, they got really tasty mint tea as well.