So, does the memory card matter much?
I think 16gigs woudl be plenty.
Does brand matter or anything else?
Do you plan on shooting burst RAW?
If so, you should get a fast card that can catch up to the SL1's write buffer from camera to card.
This is what matters most for your camera.
Ignore ratings, marks, etc.. what REALLY matters is how the card ACTUALLY performs.
This is an example video for the NEX series. You could do something similar for Canon, but this is just so you'd understand why you'd need a fast card for RAW bursts.
https://www.youtube.com/watch?v=GkgNgXqYbqk
If the SL1's are similar to any of the other Canon's (T2i->T5i, 60D, 6D, 5Dmk3), then the max speed you'd require would be around 20-25MB/s write.
Example 1: SanDisk Ultra 30MB/s UHS-I Class 10
- in this case, the 30MB/s is referencing the read speed
- the actual write speed is around 11-13MB/s, so you'd be at almost 1/2 of what the buffer is.
Example 2: SanDisk Extreme 45MB/s UHS-I Class 10
- in this case, the 45MB/s references both read
and write speed
- even though it can have write speeds up to 45MB/s, your camera can only write as fast as 20-25MB/s, so theoretically this card is "overkill"
Example 3: Sony SDHC 22MB/s Class 10
- this card performs around 20-22MB/s read, but 10-11MB/s write.
- again, not fast enough to catch up to your buffer.
Example 4: Sony SDHC 94MB/s UHS-I Class 10
- this card performs around 75-80MB/s read, but 44-46MB/s write.
- again, even though it can have write speeds up to 45MB/s, your camera can only write as fast as 20-25MB/s, so theoretically this card is "overkill"
My goal is to find a card around 25MB/s write, that is cheap. So far, something like that doesn't exist.
Best I've done is have a 32GB SanDisk Extreme 45MB/s for around $27 on sale, and the Sony 94MB/s for around $18 on sale.