Hi Master Gardener!
We are about to have some trees planted in our backyard against the back fence for privacy, and because it is a bit of a shady area (under the canopy of a large Maple tree), we are wondering if you would recommend what would be best: Cedars or Taxus (Japanese Yew).
Because your hedge will be grown in shady conditions, you may wish to go with a Taxus variety rather than a cedar. Cedars have a preference for sun/partial shade conditions, and while the Japanese Yew will be slower growing in the shade, it will eventually provide the privacy that you are looking for.
Here is a previous Toronto Master Gardeners response to a question similar to yours, and it includes a couple of our Gardening Guide suggestions, for evergreen hedges (which includes some specific varieties) and for ornamental shrubs (which can be used for hedging) for various light conditions: https://www.torontomastergardeners.ca/askagardener/privacy-hedges/
Whatever you end up choosing, do make sure that you are giving your newly planted hedge a good start by topdressing with compost or manure which will help provide nutrients for your newly planted hedging, as well as helping to retain moisture around the plant.