I am not the parent commenter, but I have the same sense that the GNU ones are better.

But the only concrete example I can think of is that `cat -n a b`, if `a` doesn't end in a newline, produces something that is obviously not what the user wanted. GNU cat does it right.

I didn't report it to the openbsd people because I didn't want them to yell at me that `-n` is nonstandard anyway with no "right" behavior, so I should STFU. Which would be what I'd expect from having reported problems in the past.

I think the behavior in the GNU clone is more consistent with "we added line numbers to the concatenation tool" while whoever added it to OpenBSD's ancestry was probably more concerned with generating listings for printing.

Personally, I'd remove even the POSIX [-u] flag from all cat versions because all of them are un-UNIX-like.

Some GNU tools are particularly ridiculous with the Easter egg features I only know about because LLMs use them all the time —and I have been using Linux for 30 years.