I assumed the question meant the computer you're currently using.
"Your computer" in the question suggests that the it is assumed that you have and use only one computer. I use several over the course of the day so could justifiably answer NTFS, HFS+ and ext4, plus FAT32 if we're to count ubiquitous portable storage devices, but we're not allowed multiple answers.
And what about the people who spend all day using their Apple pocket computers? What file system do iPhones use and why isn't that an option?