In my line of work SD cards are used for data storage and as you say it is a convenient way of transferring the data from the logger to the PC. Similarly USB memory sticks are used. Flash memory is also used, access speed being the advantage (I think but I am not sure) but transferring data to the PC has to be handled by the Logger.

SPI is not something I have used. I always used I2C as I thought it was easier to understand. I like BUS systems and serial communication in general! Transferring data using a couple of pins Is a neat solution in my opinion.