I have an Acapella, an AirPhysio and an Aerobika device.
I got the Acapella from my doctor. Of the three it works the worst. Not well designed for cleaning.

I bought the AirPhysio next. It works much better than the Acapella. It is a very elegant design that consists of two pieces of hard plastic that snap together with a steel bearing inside. It comes apart for easy cleaning.

The Aerobika was my third purchase. It is a more convoluted design made of softer flexible plastic. It has five settings but I only use the 5th setting. It has an advantage in that it can be used inline with my nebulizer mouthpiece/cup. I used it that way for a while but on the advice of a video on this forum from the doctor in Texas (I forgot her name) I discontinued breathing out through the Aerobika.

As far as their effectiveness goes, the Aerobika creates a higher frequency flutter whereas the AirPhysio has a lower frequency but more powerful pulse as the steel ball rises and falls. I think it would be akin to considering which drum in a drum kit works best the snare drum or the bass drum.

My recommendation would be to own both and see which works best for you in which situation. Neither is very expensive in the big scheme of things.

By the way, I clean my gear in a basket in my Miele dishwasher commingled with our regular dinner dishes. The dishes and the gear come out clean and sanitized to my satisfaction. The plastic on the devices has not melted or discolored.