Confused about SD Cards

For my experience:

I'm sticking with Sandisk 32GB Extreme Class 10 SDHC cards 45, 60 or 90MB/s versions.

I've never [so far, touch wood] had a problem with these cards (and i've had plenty). I am currently using a 64GB in my 70D but i have to use a seperate USB card reader to fully access the images as it's an SDXC card aand my Win8.1 PC laptop doesn't seem to like it so much, it reads/writes to it fine but always comes-up with an error message when i plug it in. I use it in a card reader as the inbuilt card-slot didn't like it (it's fine with SDHC cards) and actually it might have hurt it somehow because now when i put an SDHC into it it can only read the card but not write to it i wonder if it damaged the slot... :-/

I have tried a Sandisk 32GB Ultra card in my 650D but i found that even for still images the write/access speeds did drop as it neared the last few GB of the card as it filled so i feel more comfortable with the Extreme version.

I have also tried Kingston and Transend and Lexar SDHC cards - Kingston was OK; Transend worked OK in the camera but sometimes my laptops (Mac & PC) had trouble reading them in their slots and that was for both the 600x & 900x versions; Lexar was the worst though and my 650D had trouble writing to it as many images were corrupted so i'm never using Lexar cards again - maybe i just had the odd dodgy one and perhaps i could have sent it back to the company but i couldn't be bothered and moved on.