MCH doesn't have that much reliance on RNG anymore, we have a few GCD where we are subject too it but it's no where near as bad as it was. I consider MCH my main but always go BRD for progression - to get decent numbers on MCH you need to know what is happening in the next 15-20 seconds, a pretty strict 1 minute timer and sometimes you need to adjust accordingly before something happens or end up wasting a WF / Overheat / Screwing up timers.

BRD is a safer choice if you're not trying to push a job hard IMO.