Shooting pictures only? or doing Video? Shooting in RAW or JPEG?
For shooting continuous RAW (burst) or video, get those extreme cards.
If just shooting normal jpegs, or plain RAW, normal class 10 cards are good enough.
I personally prefer Transcend class 10 cards. Cheap and good.
I also have Sandisk normal class 10 cards (more ex than Transcend). The tests I did to compare both brands told me the Transcend are better. Just my opinion.