In the market for a new Stihl 70-80cc help !

Either one will serve your purposes and neither one is real failure prone. My wife works at the largest dealership in our area and not a lot of mtronic issues in general and the 500’s seem to be pretty good too overall. I own a ms400c and a 500i they’re both nice saws for their size, I maintain tree service saws for some guys and the one crew is up to 4 500i’s now and they’ve been trouble free till this point minus on starter rope at 5000 pulls and the same saw now got a new rewind because the spring broke. No idea on hours or pull until I see it again to scan but it’s the oldest one of the 4.