This'll be pretty "rough draft" until late January of 2021 or so...
Every film I've watched with an initial 2020 US release date, be it theatrical, VOD, or BluRay. Films that played fests in a previous year but weren't otherwise available until this year qualify for this year's list and not 2019's (for example, Color Out of Space played TIFF in September of 2019 but didn't go wide until January 2020, so it's on this list and not last year's.) Also, end of the year films that complete an Oscar qualifying run in limited release despite not going wide until 2021 also qualify for this year.

So Oscar qualifying runs, yes.... fest runs without VOD or multiscreen theatrical release, no. (EDIT: The pandemic has made this rule a bit loosey goosey this year...)

And, again, I don't do "best"... these are just my favorites