The class rating is more about data rates though to achieve higher speeds you tend to need to manufacture to a higher tolerance.

I tend to install a lot of these for media playback so a higher data rate to me is preferred.

In my experince ive only known 4-5 cards to die in the last 5 years.

Although sd cards have limits for write cycles in data sectors and theoretically have unlimited reads. When cards have failed for me in the past they are undergoing high read rates to the same sector.

Class 10 SanDisk has always been good to me.

There are a lot of fakes out there so trust your supplier

Oxford University is older than the Aztec empire.

Oxford University founded in 1326, Aztec empire ~1428-1521