I have the M21 from Audio Acrhon in Chicago. Audio Archon sells both Playback Designs and Bricasti so they are a good source for comparison info. Mike Kay was very helpful in making my decision.
I choose the M21 because of all the different options for playing PCM and DSD files. I use the M21's internal streamer with ethernet. It takes up to DSD128. For PCM there is either ladder DAC or Delta Sigma. Most of the streaming I do is with Qobuz using Audirvana. Some music sounds better with the ladder DAC and some with Delta Sigma. I've purchased DSD files from NativeDSD and used them with the 1 bit native DSD player. The Jazz at the Pawnshop recording sounds almost 3D using the DSD128 file.