Fate is pretty easy nowadays. Just start with literally any series made after 2011. They're all self contained stories that explain the premise within the first few episodes.
We're a long way from the old days where you had to read the VN if you wanted to have any idea about what was going on in the UBW movie.
But after watching Zero anything else from Fate is just weird.
Like adults murdering each other with magic and famous people makes some sort of sense. Kids doing that is just... stupid. I tried the Stay/Night, UBW many times, and it just doesn't hit anywhere near as well as the Zero did.
Monogatari was much harder for me to keep track of IMO, Fate content you can start off with most of what's available (vanilla Fate, Zero, Extra, Samurai Remnant, Prisma, Grand Order). I'd only not recommend Hollow Ataraxia or Apocrypha first.
Where typemoon is concerned, Kara no Kyoukai is more headache inducing
Fate is only difficult for people who are adamant about watching adaptations. And even though I do think the UBW anime at least reaches the threshold of "good," it's still inferior.