It can take a little while but taper off the sugar and your tastebuds will adapt. Do 2 1/2 teaspoons for a week, then 2 for the next week, 1.5 the week after etc. I used to add sugar in my tea years ago, switching to a drizzle of honey when I got to a half tea spoon, then cut the honey altogether unless I'm having green or fruit teas, then I like the honey!
I'm a big fan of roibos tea myself, red or green, and some fruit teas when I'm not drinking regular black tea.