Hi.
What do you mean by "better"? Price? Parts availibility? Ease of use? Available code/examples?
I haven't used either protocol, but SPI appears easier to implement from what I've read. IIRC, the I2C offers larger sizes. Neither is terribly expensive until you get to the largest sizes. FRAM is better than EEPROM because it reads/writes faster and has more write cycles, like 10^15 (ten to the fifteenth power!).
Do a search of the forums using "serial" or "I2C" or "FRAM" and see what you find.
Take care,
kenjj