When searching for an adjustable piano bench, it is important to know that there are actually two different types of adjustable benches: the standard adjustable piano bench, and the piano artist bench. While both are adjustable, an artist bench has a “skirt” around the lower part of the seat, hiding the adjustable mechanism of the piano bench when fully raised. With an adjustable piano bench on the other hand, you will see the raising mechanism when the bench is fully raised.
Of the two models, the artist bench is considered superior, whereas the standard adjustable bench is often cheaper in price. In terms of which bench you should select, it simply comes down to preference–the skirt does not contribute to the structural stability of the bench. If you don’t mind seeing the raising mechanism arms, then you might as well save the money and go with that. However if aesthetics are important to you, then I would recommend getting a piano artist bench. Even outside of seeing the cross-arms, the skirt around the bench makes it more attractive in general, as well as more proportional. Personally, when I look at an adjustable bench, I often think they look somewhat tiny, in terms of bulk. That is the case especially with the duet piano benches.