Downloading for offline reading is pretty much non-negotiable for me; my commute is a dead zone and my home Wi-Fi is tragically patchy. After trying way too many apps, I find the official WebNovel app handles this decently. The download icon is right there on the chapter list, and it caches a decent batch at once. The catch is you need those 'fast passes' or coins for a lot of the popular stuff, which can add up.
For a more straightforward, if less curated, approach, I use an e-reader app like Moon+ Reader. I'll find the EPUB files for completed stories from sites like WuxiaWorld, transfer them over, and read them like any other ebook. No daily check-ins, no energy systems, just the story. It requires a bit more legwork to find the files, but the reading experience is cleaner and completely under my control.
Honestly, the 'best' app depends on whether you're chasing the latest serialized updates or prefer to binge finished works. The former locks you into the official apps with their quirks, while the latter gives you freedom at the cost of convenience.