Would highly recommend Quarq.
I have been using a DZero since January 2017 and it has been flawless in recording power (unlike Garmin Vector 3 which remains unreliable even with new battery doors). The CR2032 lasts a long time and is easily replaced, even during a ride (you obviously don’t want to stop and exchange during a race, but for audax a spare CR2032 is part of my kit)
The Quarq did develop play in the left arm, both rotational and sideways. Most likely because I swapped the crankset between bikes quite a lot and may have forgotten a washer or two after a while. Unfortunately this happened when the cranks where some 2 1/2 years old, so out of warranty.
When I contacted Quarq I got a response quickly and learned that a) a replacement crankset (without the power meter) was expensive and pretty much only available from Quarq themselves, and b) that SRAM cranksets could not be used as an alternative (IIRC they use fewer bolts to fix the spider, which makes the meter inaccurate). But then I got an e-mail from the guy I was corresponding with that he found a pair of blemished cranks that they could send me. They even paid for shipping from the US to Europe! (and I had to look really close to spot that blemish…)