Sequential read:
HDD - low 3 digits MB/s
eMMC - low-mid 3 digit MB/s
SATA SSD - mid 3 digit MB/s
eUFS 2 - high 3 digit MB/s, possibly hitting 1,000
eUFS 3 - theoretical max of 2,100 MB/s (realistically, probably average out to high 1,000's/just under 2,000?)
edit: theoretical max of 2,900 MB/s by spec. I pulled 2,100 from Samsung's own chart
here
PCIe gen 3 - theoretical max of 3,500 MB/s
eUFS 4 - theoretical max of 4,200 MB/s
PCIe gen 4 - theoretical max of 7,000 MB/s
PCIe gen 5 - should be a doubling again? But current controllers are stuck at either 10,000 or 12,400
Random IOPS (Input/output Operations Per Second):
HDD - 2-3 digits
eMMC - high 4 digits/breaking into 5 digits
eUFS - climb their way up through 5 digits, 3.1 possibly hits 100k random read
SATA SSD - up to high 5 digits? (Crucial MX500 gets up to the 90k range)
PCIe gen 3 - mid 6 digits?
PCIe gen 4 - high 6 digits/breaking into 7 digits?
PCIe gen 5 - low 7 digits?