When we were looking for walkers and mobility aids, we came across the U Step. We heard great things from people about it but never was able to try it with my mom. Unfortunately by the time i discovered it we needed a wheelchair not a walker. However I have personally seen and tried one once and can easily say it is the Cadillac of walkers!! For PSP, MSA, CBD it has many features to help with symptoms of the disease and adjust as it progresses.
Here is a link to it and all of the features explained.
Note: Check if your insurance/Medicare will cover or help with cost. Some coverage will only cover one large mobility aid every 5 years. With Atypical Parkinsonism sometimes you need 2 large mobility aids in less than 5 years, due to progression. Make sure to ask, as some evaluate Parkinson and/or Atypical Parkinsonism as an exception and will allow it on a case by case basis.