Quoted from Rarehero:
I guess you've never seen a routed B/W games? Yes, Williams games were generally engineered better...but plastic is plastic, welds are welds, mechs are mechs...shit breaks over time. I picked up a Monster Bash that was completely trashed and 95% of the switches didn't work.
Gottlieb games were generally engineered better. Actually, like, always. They just didn't earn worth a damn, so no one remembers them.
B/W games often showed up with switches out and issues, but because they earned well and kept earning well, people kept them around.
DE games often showed up with switched out and issues, but earned like CRAZY for a while, before they dropped off and people didn't route them as much.
Sega games greatly improved on the reliability factor of the machines, but generally earned poorly again. And yes, I know they were DE that just changed, they just changed their philosophy at that point.
Stern kept the Sega reliability when the company name changed again, and started working on improving the fun factor.
Today's Stern games are the most reliable games out of the box there are. A lot of people give B/W a pass because they either were routed so of course they are broken, or they got completely rebuilt and tweaked by someone who knew what they are looking at. If you ask ops who routed all the games at the same time though, they will confirm today's games are the most reliable out of the box.
(This has nothing to do with "flipper feel" or whatever, but is just an interesting thing...)