my preference would be same brand of machines in the laundromat.
mix and match just be too troublesome, from keeping parts, uniform operations, customer issues, etc...
yes, some customers have a perception that a particular dryer is much better than the others, even though all the dryers are the same brand and programmed the same way. in my mats, each one has a favorite dryer and washer for the customers; they are not necessary the one closest to the doors either. seems like it's a psychological human behavior
someday, if space permitted, i think building a mat using the concept of assembly system might work well. that is by having all the washers at the entrance door and having all the dryers in the middle, then all the folding tables at the exit door. so you would need two doors for access