Transfer bench - make sure the inside legs have an adjustable height independent of the outside height. Most newer bathtubs don't have a bottom that is level with the floor outside the bathtub.
Burden
Does not work well if you have sliding shower doors.
I couldn't find a way to use my shower curtain "around" my transfer bench that sits partially outside the tub (only up to the front) and often got the floor and outside wall wet when using my handheld shower.
I use a plastic patio chair; we have a big enough shower to accomodate it. It's nice.
When I wash my hair; I lean back without worrying about falling. We have a regular
sized shower head for my husband on wall, and an adjustable hand held head on the
wall so I can sit and shower & shampoo. It's great!