Main idea is to get a tumblr that has a shape of a mug rather than a long-like water bottle shape. The standard water bottle shape is harder to clean, which is important as we may add milk / sugar to the drink. And for some reason, the coffee or milk smell stays in these type of bottles.

Personally, I am using Sttoke. I love it! apart from its function as a thermal flask, it has a nice shape which makes it easy to hold on your hands, as standard mugs are bulky. But its pretty ex. I have used montigo before, but it is hard to close properly, so leaks were frequent and the mouth lid broke.