Bulletproof. Seriously. Nuff said.
I had the same good fortune with them. Lasted 15 years (washer) doing big loads often. The dryer went even longer (I replaced the element once).
When we had the money, we replaced them with the ('water saving','energy efficient',) Whirlpool Duet, washer and dryer pair, which quit in two years, washer first, because of motherboard issues, and which had other problems on the way, from eating socks to shredding clothes, then the dryer which had an in case flash fire because there was a 1/2" gap between the filter housing and vent pipe, which eventually filled the case with very fine lint. (Most acrid smoke I have ever come across, and I was a firefighter for four years). The MOBO went out in that, too, not long after cleaning it out, checking all the wiring and closing the gap in the vent line.
Never again.
Currently running Amana and after five years of hard use I hear some backlash in the gears on the washer (top load, big tub), and on the dryer, have replaced the drum rollers, refurbished the timer, and replaced the door switch, but those machines have been running almost 8 hours a day since we got them.
In the meantime, I keep my eyes open for another pair of Speed Queens in case...because I can open them up and fix them.