it depends. mainly bananas are always my base because they are denser calories and cheap for me i get a 40lb box for about 6-12 dollars. From there I add on whatever other fruits i have handy. I'll also toss in kale or spinach or hemp protein from time to time as well.
Some of my favorites tho are banannas and blueberries with a touch of hersheys unsweetened cocoa theres plenty of sugar in the smoothie to keep it sweet and toss in a few dates.
The same thing but with raspberries instead of blue berries is good or strawberries.
I think the kicker is if its going to be a meal or not or if this is going to be how one eats through out the day. Then portion becomes pretty critical. I'll routinely have a 64 ounce smoothie for a meal. This can hold me to the next meal with minimal snacking at times tho I have no issue piling in more fruit between meals.
A lot of people have issues becuase they will not eat enough OR getting that 64 ounces down is a big struggle. It gets easier in time. Also keep in mind with how i run these kinds of meals are like tyring to put out the sun with a drop of water. I'll just torch it all off in no time flat.
But dont expect a smoothie with like 3 or 4 bananas a handful of kale and a couple strawberries to be much more then a snack. It is possible to starve despite having a full belly this is not a good feeling lol.
the big thing in the groups of people that eat like i do is if your craving garbage food you probably didnt eat enough. If your tired you might not have eaten enough. if your sad maybe you need more carbs if your depressed perhaps you should eat more fruit etc.... Almost as if no matter what your ailment is maybe try another banana and see if that helps lol.
I know i've read stuff about carbs and sugar making people happy so there probably is something to it.