i gave up 2 sugars in my tea a few years ago before diabetes, it took months to get used to it but if i accidentally sip the wrong cup of tea at work with sugar in it, it basically tastes like hot sugar water, its nasty, id say go cold turkey, maybe dont drink it at all for a fortnight to unaquaint yourself with the taste, the benefit is, once youve kicked the sugar habit you can actually taste the tea, its so much nicer
another vote here for green tea but you have to experiment on flavours, my favourites are lemon or cranberry green tea, without the flavours it tastes a bit like dish water to me but i love it and drink 10 cups a day at work