Well, depending where you head after either Salzburg or Innsbruck matter also.
Salzburg is obviously less travel time to reach.
We’ve been to both many times and twice in late November, early December for the Christmas markets. During the markets both are spectacular, but since we love the high alpine scenery we give Innsbruck the edge.
That said, if you have a clear day and plan on spending it cruising the Wolgangsee on a lakeship, visiting St. Gilgen, Strobl and St. Wolfgang, well, I’d go with Salzburg and a day on the Wolfgangsee. We did this on a Christmas Market trip and it was spectacular. Lake, scenery, the villages and especially the “old town” of St. Wolfgang. Plenty of big windows, food, baked goods, drinks on the lakeship!
Paul