I really recommend hot water, but you have to add something else if you don’t want it to taste bland, I add mostly banana, berries and dark chocolate, it’s delicious!
Try different milk alternatives! I personally love almond milk, especially the one that has vanilla in it. Soy milk is pretty good too, but if you really want to go for the meme, try oat milk with oats!
If you don't like adding milk in oats then you can add warm water with milk-powder or just warm water or, You can also add chocolate syrup.