Welcome to one of my favorite foods, I always buy the plain! I usually eat it with a banana and 2.5 tbsp of hemp seeds.
Since it is thicker it may taste richer. And because it’s concentrated, it’s higher in protein than regular yogurt. If you want even more proteins, you can even mix it with protein powder. Not a big fan myself, but a friend of mine like such kind of shakes.
upd: another delicious thing just came to my mind. For a smoothie that replaces a meal I’ll mix one scoop (vanilla or cookies and cream) with plain non-fat greek yogurt, a half-cup of oatmeal, some raspberries, and a little non-fat milk. Calories, calcium and protein. Yum!