I have tried lots of different teas over the years - I used to work for Allied Lyons - and seem to have settled on a mixture of mint and liquorice as my all time favourite.
I can buy the two teas in Tesco and put two bags of each in a large teapot, not quite boiling water, allow to infuse and then I fish out the bags and keep it warm over a tea light. Now that winter is on its way I will be adding that to my menu. It doesn't need any sweetener - to my tastes, though boiling water and long infusion do bring out the bitter flavours.