While there are certainly plenty of flashy power meters on the market, you're right to prioritize durability over bells and whistles. From my experience as a helicopter pilot and avid cyclist, I can tell you that there's no substitute for reliable, rugged equipment that can withstand the rigors of heavy use.
When it comes to power meters, I've had great success with Quarq. Their power meters are built to last, with a reputation for durability that's well-deserved. I've put mine through some serious punishment over the years, and it's never let me down. Whether I'm racing in a triathlon or just training on my own, I know I can count on my Quarq power meter to deliver accurate, consistent data, even in the toughest conditions.
Of course, there are other durable power meters on the market as well. SRM and PowerTap are two other brands that come to mind. Both have a long track record of producing high-quality, reliable equipment that can stand up to heavy use.
That being said, there are certainly some power meter brands that you'll want to avoid if durability is your top priority. Garmin, for example, has had some issues with reliability in the past. While they've made improvements in recent years, I still wouldn't recommend their power meters for anyone who needs equipment that can stand up to heavy use.
In short, if you're looking for a power meter that can truly stand the test of time, I'd recommend sticking with Quarq, SRM, or PowerTap. These brands have a proven track record of producing high-quality, durable equipment that can withstand the rigors of heavy use. Avoid Garmin and other brands that haven't yet earned a reputation for reliability, and you'll be well on your way to finding a power meter that will serve you well for years to come.