SQL left join vs multiple tables on FROM line?

Question

Most SQL dialects accept both the following queries:

SELECT a.foo, b.foo
FROM a, b
WHERE a.x = b.x

SELECT a.foo, b.foo
FROM a
LEFT JOIN b ON a.x = b.x
         


        

Answer 1

I hear a lot of people complain the first one is too difficult to understand and that it is unclear. I don't see a problem with it, but after having that discussion, I use the second one even on INNER JOINS for clarity.