I use a Ninja that is several years old and has the puree cycle. Not sure itis still available but it has been a workhorse for us. We bought it after wearing out the blender top on one of the expensive ones and finding the replacement part over $100. I think it was about $130 on sale - I'm sure the price is higher now.

Sue gave great options for putting into a smoothie. I usually keep a few bananas, broken into chunks, in the freezer to throw in. Adds a little bit of sweetness and makes it creamy. When I use frozen fruits I don’t need to add ice. Usually use almond milk or keefer as a base but any juice or liquid works. I also like to throw in a little almond or peanut butter. I also used to drag out the workhorse blender but now use my Ninja bullet blender which works great for single servings.

All have given you good advice.
My addition for what it is worth. I prefer protein powder that is not whey based, which is dairy. I prefer greens for protein powder and things like pumpkin.
Also, the banana is good for two reasons....potassium which we need and also helps with clearing us out.
I also just use water rather than a milk product of any kind as the liquid. The water I use is that which I boil to make sure any bacteria is hopefully boiled out. You will notice on this site that we concern ourselves with being sure we have bacteria free water.
Barbara