I'd go with either Firefox or Thunderbird. Both are immensely useful pieces of software that I use on a daily basis, and have evolved (mostly) nicely over time.
Not to give Mozilla too much credit, Nextcloud is also pretty slick!
These days, being an open-source browser that isn't part of the Chromium monopoly is pretty much the only good thing they have left...
That is a good point, and in my experience Firefox has just kinda sucked less in the last couple of years. But of course that's anecdotal so doesn't really mean much lol