I made smoothies every day for years. I found the waring blender, taller more narrow shape worked much better than the kitchen aide style which is shorter and wider. I always had chunks that weren't "blended" in the KA, and I had at least two of them. On the down side, the Waring is really loud but it did a great job and didn't leave a chunk of banana ,for example, floating intact after several minutes of processing. didn't even have to be frozen banana. so I personally think the shape of the container is important & I would go with the Waring shape. unless of course I bought a $400 vita-mix.
"If the world were a logical place, men would ride side saddle." Rita Mae Brown