I've used in the past sandisk cards, And They are an excellent choice. I did Experienced Some problens with two of 'em so I've switched to Lexar cards pro 2 years ago. I own 2 cards and 8 16g 32gb cards, all of 'em have a backup card, since I can write to the files Both CF and SD slot on my 5d m III They are very dependable, since I Had No glitches or any kind of problems in the past 2 years of use. Since I do weddings I Can not Afford missing data, so this is really a big deal for me. I really can trust thesis. Speed wise, I Normally do not do a lot of FPS, except on Some situations like throwing rice to bride and groom, and the card can keep up with the speed of my 5d burst mkIII. A special note on this one, the mkIII really is a speedy camera on this department, purpose When writting raw to CF and SD cards at the same time, It Does lag a little bit Because of the writting speed SD card (I think the 5d can not write faster than 133x Any SD). This card is really worthy of the 5 stars. On the downside, all of my cards are scratched and loosing the gold finish on the labels. My old sandisk cards are still looking fine. Lexar address shoulds That They Could loose since second hand value, if you INTEND to sell 'em later (In Spite I do not care How They look just as long They perform well). Bottom line, this is a great buy.