Card selection does not only depend on your camera, but also on your computer, most specifically on your card reader, which you may also want to upgrade.

You want to select a card that has fast enough write speeds not to be a bottleneck for your camera. Camera reviews should report the write speed of the camera, so you have an idea of what cards to look for. However, faster speeds generally command higher prices, so you should not just blindly buy the fastest card possible. It is also unfortunately possible that the most-recent, fastest cards do not work as fast with an older camera. The only way to know is to test several cards in the camera, and report results. Few sites do that thoroughly (see below for one that does).

There is also value in being able to read your card quickly on your computer. There is a dramatic difference in speed between an USB 2.0 card reader and a USB 3.0 card reader, and for the same price and same write speed, two cards might differ on the reading speed. As with cameras, the only way to know is to test several cards in various readers, and report results. As with cameras, few sites do that.

One web site stood firmly above others when I investigated those questions a couple of years ago, the appropriately named http://www.cameramemoryspeed.com/

Apparently run by fellow geeks (note that they do make money with affiliate links on that site), it goes way beyond other web sites when it comes to testing cards:

• They test cards in many card readers and many cameras
• They test cameras with many cards (average write speed and continuous shooting test)
• They test card readers with many cards
• The results are provided in nice sortable tables

As a practical example, it allowed me to select an appropriate card for my Canon 6D, which is a camera that writes 36 MB/s at best. For this camera, one particular brand of cards works significantly better than others: SanDisk. Within that brand, a couple of "intermediate" (45 MB/s, 60 MB/s) cards were 50% cheaper than the 95 MB/s top line with almost the same write speed in-camera. Actually, the 80 MB/s and the most recent (and most expensive) 280 MB/s card perform worse in that camera!

So, a possible workflow could be:

• Get the camera write speed from reviews
• Consult the site above (or similar ones, if they exist) to determine the three or four cards that seem best for your camera
• Shop around for the best prices on these cards