Ok, they are not all the same...there are extensive tests out there demonstrating the differences. If you need speed (to shoot continuously, record video and transfer to your computer quickly), do your homework. I did a bunch and went with a pair of Lexar 32gb 800x cards for my 7d and have been happy. I've got over 50,000 images on each of them with no issues.
FYI, Lexar use NAND from Intel/Micron, controller from SMI. Unless you shoot RAW HD video, which requires you mod your canon body with magic lantern, there is no need to be faster than Class10, which is a 10MB/s write for a specific data pattern.
Video doesn't require a fast card. Anything over about 8 MB/s will be more than enough.
Video require certain class speed that is specified by your camera. Class speed is NOT sequential write speed.
Having that said, you can NOT have slower sequential write than Class speed, meaning a card that capable of 8MB/s sequential will NOT meet class 10 for sure. The opposite is NOT true, meaning you can have a card capable of 40MB/s in sequential write but can't meet class10.