Personally I download fanfiction then read it on Moonreader+. It let's me customize each fanfic font, background, color, and other features like the best text to speech for speed. It also has a speed reading function. I honestly have a hard time reading on the site because I'm so used to it. Other text to speech apps are way to slow for me.

Anyway I'm curious if other fanfic readers have a particular way of reading that they have a hard time doing it any other way