Given a choice it is always better to eat something raw, especially when its a highly nutritive herb like Nettle. Cooking is such a waste, but I admit cooked nettles are even better than spinach-they get slightly thicker, very filling.
Take off the stem. If they are young you wouldn't need to I suppose. But for many plants the bad constituents are in the stem, plus the extra fiber to reduce juice yield.
Like horsetail only consume before the summer solstice, early Spring best.