Tea has far less caffeine in it than coffee, so a couple of cups a day are unlikely to be any sort of a problem, and the anti-oxidants, as you say, will do you good.
I think green tea partly has a very good reputation for its health benefits because a lot of the research into the health effects of tea have been done by Japanese scientists, and the japanese drink their tea unfermented (i.e. green), so that's what they looked at. It may be a bit better than black tea, but if you really prefer tea black ...
Black tea is traditionally in many cultures mixed with other foods—milk, cream, butter, salt, sugar, jam, citrus fruit. It has a less delicate flavour, so that's probably why it's often mixed with other things. In Victorian times in England hostesses used to pour tea and then hand it round with a jug of cream and a dish of lemon slices, so the guests could take which of the two they preferred. People working in fields often took it black (either hot or cold). Quite when most people started using milk instead of cream I don't know.
I haven't used sugar in drinks for years myself and now prefer the taste without—I think you just get to like whatever you're used to to some extent. But I guess a pinch, as opposed to a spoonful, isn't going to do much harm. I have drunk black tea with a half-and-half mixture of single cream and full-fat milk, and I quite liked it, but I found the tea needed to be quite strong to compete with the taste of the cream.