Black tea, no sweetener. Water.
Stevia tastes like saccharine.
Stevia is bitter.
For me Stevia leaves a mildly bitter aftertaste. I’ve lately been experimenting using a Monk Fruit sweetener mix (available in a mix with erythritol, the main ingredient in Swerve). It’s extremely sweet with no bitter aftertaste I can notice. But drinking unsweetened coffee, tea, and water only, I use any sweetener rarely, for things like Christmas cookies or Thanksgiving pumpkin pie and whipped cream.