1. Mocha: Mochas have chocolate sauce added to them, but are not very sweet.

2. Macchiato: The Macchiato is a coffee with caramel, so it's the sweetest compared to the others.

3. Cappuccino: Cappuccino is made with more high temperature steam milk froth, but not too much added sugar, so it is relatively sweet.

4. Latte: Latte is coffee with regular plain milk, no added sugar, so relatively bitter.

The acceptance of the bitter flavor may vary from person to person, but in general, lattes, because of the lack of sugar, may be a bit more bitter compared to the other ones.