Great discussion on Facebook:
Lots of guesses and questions on the benchies.
Well here is the printers used per benchy:
a) MonoPrice (MP) I3 flexion extruder
b) MP Select mini
c) MP I3 Stock
d) Prusa MK 2
e) Wanhao I3 +
Thanks to all who participated in this thread.
I will be posting more on these benchies, looking at each in detail and then tweaking the settings for each to get a better print.
I also have comparison using the Prusa Mk 2 at 200/100/050 Microns.