There are many policy cards in Civ 6, yet once you grow used to a certain play style you always pick the same ones. For example, I always start out with Discipline and God King, unless I can generate faith some other way.

Some cards have changed recently. Veterancy now applies to both Harbours and Encampments - a straight 30% production bonus both to districts and buildings. Quite strong and unique.

Some policy cards are extra powerful in bursts, such as Feudalism in tandem with a monumentalism golden age.

Other policies become great when all your cities have something in common - like Hansa. Craftsmen is situationally useful in general, but really fantastic with Germany, since you will have a Hansa in all your cities. Compare Urban Development's 1 hammer per city to Craftsmen's 4-10 hammer per city for Germany.

I also found it incredibly difficult to find a list of all the legacy policies. Classical Republic's legacy policy ( 1 amenity and 1 housing from the first district) is really strong, and Oligarchy's gives a 4 bonus to melee units, but what about the other?