I drink a lot of different hot teas. I dislike the Orange Pekoe that is commonly served in northern state's restaurants. Orange Pekoe, Earl Grey, Morning Breakfast tea, and many other black teas have fewer benefits than green teas. Black teas are made from leaves that have been allowed to ferment before being dried. That fermentation process reduces many of the antioxidants and vitamins that can be derived from drinking tea. There are many formulations of green teas that have added vitamins or inherant vitamins. I have found that drinking Red Rasberry tea seems to help suppress my appitite more than many other teas. I also thoroughly enjoy any teas with mint or camomile in them when I have a cold. The mint and camomile seem to help my sinuses more than just the hot liquid itself. Granted some of that my be psychological but it doesn't matter to me so long as it helps me feel better and isn't harmful to me.
Fennugreek tea is supposed to help digestive tract problems, Comfrey is helpful with allergies, and Eyebright is supposed to be useful in managing morning sickness and nausea in pregnant women. All of these claims have not been proven by massive studies as are conducted for standard medications and the benefits are much less dramatic than medication. Still try different teas and pay close attention to your body. See what works for you and what doesn't.
As for causing cancer - I honestly had not heard that claim but then again it seems like anything in excess can cause some sort of physical problem or cancer. Just drink it in moderation and enjoy.
I have made my own teas by drying my own leaves. Clover tea is sweet and pleasant to drink. Mullen tea has been used for ages even back to Native Americans as a remedy for lung problems (asthma, bronchitis, colds) and does seem to give some relief. Rasberry leaves make a tasty tea. There are many natural plants that can be used for teas.
This site has some information on plants useful for making your own tea.