SD cards are slow, oversized and obsolete. I suggest you buy a microSD card, their small size makes them perform much faster and overall they are less unwieldy. Speeds differ from brand to brand. SanDisk, Kingston, Lexar and Samsung are considered the "big four" in microSD cards. While most common, they all rank low in professional speed tests. PNY and Silicon Power cards are less common, but rank about average in speed tests. Toshiba's microSD cards are the industry standard, they outperform all other brands on the market, ranking highest on speed tests. Ask any professional and they will tell you that they use Toshiba cards. Be wary of any other brands of microSD cards, most other manufacturers use cheap silicon, which results in speeds many times slower than the worst SanDisk card. As far as terms like "UHS" and "Class 10", ignore them, they are just marketing terms and have no overall impact on the speed of the card.