I like peppermint tea at double strength with no sweetener. Also, teas with Rooibos (I don't know if I spelled that right, but they're also sometimes called "Red Tea") tend to be very delicious unsweetened (the Rooibos is a naturally sweeter herb).

Also, have you considered Stevia? It's not an artificial sweetener in the mode of Equal/Sweet 'n' low, it's actually extracted from a plant and has little to no impact on blood glucose (which means it might not trigger your sugar cravings). I've been using it off and on since long before it became "the new thing." Probably since the mid nineties.