Can't tell what brand it is (AT&T doesn't make SD cards). I buy SanDisk (I paid only $25 for my SanDisk 64GB SDXC card) - and in a couple of decades (I started using them soon after they first came on the market) the only one I ever had a problem with was a microSD card that I cracked in half. My 256MB full size card still works (It's too small to be useful for much these days, but it's so far outlived its warranty that I consider it free.)
(BTW, if you're buying large cards, you want SDXC, not SDHC.)