I always pipe from cat, as a matter of habit.

Reason being: I've probably just catted the file at least once, and it's even likely I catted it right before piping it. So I can extend that command from the history, and if I keep piping (likely) I don't have the weird syntactic stutter at the beginning where `blah < file.txt` | next` puts things out of order.

Also, you can't mistype `cat file.txt | blah` and overwrite file.txt accidentally with the output of blah. That's ergonomic.