Well, from a development perspective a SD card is a lot nicer because you can pop it out and write it easily if you brick it, whereas eMMC requires fastboot or

Well, from a development perspective a SD card is a lot nicer because you can pop it out and write it easily if you brick it, whereas eMMC requires fastboot or weird OEM loaders that only run on 32 bit XP on Tuesdays. Also, eMMC's bus can reach higher speeds than SDHC, but that is only useful if you get an expensive and fast eMMC. I have used embedded boards where the eMMC was slower than a Sandisk Ultra microSD card.