EDIT 6:26am PT 8/3/2020: Corrected title and clarified details.
When you're at the cusp of making a GPU purchase decision, it's easy to blindly stare at the performance figures and use that as the only metric. However, there are other factors that you have to consider, which include reliability. In that vein, Mindfactory recently published its RMA data for Nvidia Turing GPUs and AMD's 5000 series, and while it's discouraging news for AMD, Nvidia doesn't escape unfazed, either: The 2080 Ti had that highest RMA rate of any single family.
Mindfactory is one of the bigger hardware retailers in Germany, and they sell much the same hardware as we have in the U.S. The data it gathered comprises Nvidia cards from the 1660 Ti and above, with AMD's data includes the 5500 XT and above. The full list is available here.
In total, the data set covers 44,100 AMD cards sold and an impressive 76,280 Nvidia GPU, so it is clear that German buyers prefer Nvidia GPUs. From these figures, Nvidia has a total number of GPUs RMA'd of 1607 units, and AMD a total of 1452 units -- which translates to a 3.3% RMA rate for AMD and a 2.1% RMA rate for Nvidia cards. That means that the AMD cards sold through Mindfactory had a roughly 50 percent higher RMA rate.
However, it's also interesting to look across the product stack and see where the failures happen. Nvidia line is quite consistent throughout, but in AMD stack it's clear that the 5500 XT cards hardly fail at all, while the RX 5700 and RX 5700 XT cards fail most with a 3.6% failure rate, which isn't great compared to the RTX 2070 Super's impressive 1 percent RMA rate.
Jump to an RTX 2080 Ti though, and you're looking at a painful 5.3% RMA rate. That's the worst RMA rate for any single family on the list.
Of course, it's important to mention that these numbers alone still don't tell the whole story. Many Redditors rightly point out that AMD did have problems with the drivers early on with the RX 5700 series releases, which might explain why the RX 5500 XT has a lower RMA rate, as it came out later when AMD had more time to refine its drivers. Mindfactory is also not the largest retailer and serves primarily the European market, so it's possible the retailer simply received a batch of cards that suffered from a production issue, whereas other shipments may not.
Meanwhile, it's also not specified why the different cards were RMA'd. For example, I have an RTX 2070 Super from Gigabyte in my system that has a broken fan bearing on its WindForce cooler that I still need to RMA, but this could just as well have happened on the AMD variant of the card as the coolers come out of the same factory -- but we can likely presume that those kinds of minor defects occur at similar rates between Nvidia and AMD cards.
At the end of the day, the best thing you can do as a consumer is look at reviews, including customer reviews of the card you intend to buy -- a lot of negative feedback is a simple red flag to watch out for. If you're buying at the release of a new product when there aren't many customer reviews yet, well then you're probably aware that you're taking a higher risk to begin with.