For what it is worth, I have used both methods, card readers and direct connections. Perhaps about 50/50? I have had a few corrupted videos and photos, but maybe half a dozen out of 200,000 or so that I have processed in the last few years? The only disaster was the loss of a few hundred wedding photos I once lost on a backup drive--only backed up one place because I was in a hurry. The client never knew the difference (I had plenty more good images), but to this day, I do!
I have had cords jerked out while transferring, Pepsi spills, you name it, rain, bitter cold (-50), monsoon rains, desert sandstorms, and my images have pretty well survived them all. I use middle-of-the-road quality cards.