Or, how about something completely different? And I mean, completely different.
The most engaging I have read (and in fact still am reading) happens to be a web-serial. It beats everything I have read before. Period. Seriously. But, seeing here on this site how preferences and opinions can differ, it probably isn't to everyone's taste.
The downside of a web-serial is, obviously, that it's all first draft. There simply isn't time to rewrite every chapter if you have committed yourself to publish 2 chapters every week. Chapters that often exceed 20.000 words. Having said that, the story and storytelling is nonetheless compelling and engaging. Once I was past the first few chapters I have not stopped looking out longingly for the next installment. The quality of the writing has improved majorly over time.
You wanted a long story? How about something over 8 million words and ongoing?
The world-building is complex and extensive, covering many races worldwide, their culture, characteristics, and shared history. All the characters are distinctively recognizable and have their own quirks. The ongoing story is, certainly in the beginning, interspersed with 'slice of life' chapters, often funny or moving, that helps picturing, understanding and appreciating the characters. The dialogs are never boring, repetitive or superfluous, but bring the plot forwards.
The story takes place on a world with game-like mechanics. People get [Classes] with levels and [Skills]. It is
not a game, though, or anything to do with roleplaying. Everything is serious business and often deadly as well. Situations can get tense. Also there is magic. Clearly it is not Earth, it inhabits many legendary creatures and monsters, but whether that suggests some connection with Earth remains unclear.
The story starts with the main character, a 20 year old girl, suddenly being transported from Earth to this strange world and since struggles to stay alive. It slowly becomes clear she is 1 of a 1000 youngsters who have been abducted and of who many died instantly or soon after.
Who or what is behind these abductions is one of the mysteries that needs answered. One of the many. It starts simple, straightforward and focused on one character, but it grows and turns out to be a really complex, well thought out story.
Anyway, enough said. Check it out for yourself. It is free for your perusal, on this website
The Wandering Inn