These produce exactly the same query plan.
The former is the newer style, SQL-92 JOIN syntax, where the latter is "old style" notation.
There is no accounting for taste, but I prefer the newer style, as it separates the predicates used to define JOIN criteria from WHERE predicates used to select rows from the resultant JOINs. If I have a complex WHERE clause, I like to keep it focused on row selection rather than JOIN definition.
The old style begins to show problems when used in OUTER JOINS (*= syntax). There, true ambiguities can result depending on the order of WHERE clause evaluation. Removing these ambiguities was the main reason why the new syntax was proposed.
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