FSN: Went through it in Japanese not long ago.
Fate: 6/10, UBW: 6.5/10, HF: 9/10, HF is hilariously better written than the rest and pretty much the only route where Nasu actually tries.
I tried to go through Tsukihime again recently (in japanese once again) but I stopped a few hours in, it's pretty much unplayable these days so I'll just wait for the remake.
Mahoyo: 7.5/10 Great production, great soundtrack, the pacing in itself isn't too bad as well and the plot, while basic, serves its purpose.
But the writing just doesn't follow, it has a 3rd person narrator which I personally think can be a great strength for a writer but it's used in a pretty bland way here.
Basically the narrator is just used to describe every details, every movements in the most detailed way possible and to state the obvious, there is no imagination, no emotion, all this make for a pretty dreary read.
Add to this that the characters aren't really the beacon of interesting and the dialogs are pretty bad, even the narration during the battles really doesn't translate the action that well (though they are still amazing to watch simply due to the production).
Also FHA: 8/10, I liked the main story better than Fate/UBW and the Avenger/Bazett/Karen trio is actually entertaining to watch.