Based on information provided in this link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3948928/table/Tab1/
fMRI data can have the following data types: 
Signed and unsigned integer (from 8- to 64-bit), float (from 32- to 128-bit), complex (from 64- to 256-bit)

I'm wondering which data type is more common? almost all the datasets that I have seen so far have floating point values. 
What is the data type of data that is acquired with newer scanners? Why different datasets could have different data types?