I like both. In fact I have a schedule!
early morning- black tea
mid-morning- coffee
lunch- coffee
mid-afternoon- green tea
dinner- black tea
black tea with milk and honey, coffee strong with a little milk only (hate sugar in coffee) and green tea plain.
A nutritionist told me that your body builds up a tolerance to caffeine, so you don't get dehydrated so long as you don't go over your 'regular' daily amount.