It all depends on the type of tea I am drinking!
I love freshly brewed leaf tea of various blends, and when they are fruity or have lavender flowers in,they do not really need to made sweet with anything!!! I do sometimes use a very small amount of either honey or raw sugar
in plainer tasting blends,and also sometimes when I am feeling more tired than usual and need a bit of an energy burst!!
Cannot stand sweetner of any description. Only drink weak black tea or Chinese green tea. I think the problem with adding sweetners starts with parents adding sugar to tea for children to drink. A habit formed when young is hard to break.
It really depends on the type of tea. For herbal and flower teas, I don't add any sugar or milk. Some red and black teas can be drunk without any sugar or milk too! I personally like my earl grey with a slice of lemon. English breakfast and Assam is nice with milk and sugar :) But that's just me :)
I have no idea how people drink tea and coffee without sugar or any other sweetener. Working a lot with your brains require a fair amount of glucose daily. I love the strongest black tea and can't imagine it without a spoon of agave syrup, it gives the black tea a rich and bold taste, you can't have enough of it. If there is no agave, I use honey, but never sugar or milk. I think the milk is the one that spoils the taste of a nice cup of a strong black tea, it turns it into a baby food mixture. Having tea without sweetener is like soup without salt or a kiss without a hug.