Sandisk ultra is more reliable OTG pendrive can be used for both the pc as well as micro usb for the Mobiles, Tablets etc. It has pretty good transfer speeds for PC but for mobiles depends upon the processing speed of the mobile. Performs well with my Motorola G 1st gen.
Mobile sometimes copying speeds will be very low nearly 700KB/s. Works will all OTG supported devices. Designed to perfection can also used even after washing it in the washing machine.