From the reviews linked from this thread, it appears that the MASTECH MS8218 quality and design may not be as solid as the Brymen or Greenlee?
Mastech is a typical Chinese multimeter, i.e. quality and safety is lower.
But then the warranty might be an issue
It is very seldom you need warranty on a multimeter, but if you want warranty, go for Greenlee, it is the same meter.