The only one I have tried is Chris Christensen's "dry shampoo" and I didn't like it. Smelled very chemically to me and didn't really do much. It's a spray that doesn't require rinsing.
I prefer to give body washes, or partial body washes, and use a wet washcloth on the beard as needed in between full baths.
I would avoid using baby powder. Not good for the doggies to ingest or inhale. Corn starch, I've used for detangling. Neither is helpful for urine or anything on the rear end, if you know what I mean.
