There seems to have been a migration over time from the first format to the second, perhaps a result of C programmers not having a keyword "then", which Bourne shells (following Algol 68) require.  I don't think it matters much.

On Tue, Sep 29, 2020 at 2:52 PM David Barto <david@kdbarto.org> wrote:
In a brief discussion with a coworker today the question of formatting shell scripts came up.

I believed that in the past the preferred format (if there ever were any such thing) was

if [ test ]
then
        statements
else
        statements
fi

I can find nothing specific to back this up. More appropriate for COFF maybe would
be a discussion of what format is better

if [ test ]; then
        statements
else
        statements
fi

or the above.

No intention to start any kind of flame war about which is better, just want to see
if there is any historical option for one over the other.

        David