Looking for epic book series

Recently I'm trying to find epic (in terms of volume) series to
read with very complex story arc, probably Sci-Fi, but I wouldn't care for Sci-Fi if it would fulfil the other two requirements.

After quick research, I've started reading `Book of the New Sun'
by Gene Wolfe, with intention of reading entire `Solar Cycle'
series.

Right now I'm in the middle of the `Claw of the Conciliator' and
I'm loving it, although I begin to realize that `Solar Cycle' is
not exactly what I was looking for. (I'll finish it nonetheless.)

First of all, `Solar Cycle' consists of `Book of the New Sun',
`Short Sun', and `Long Sun', all of which take place in the same
universe, but I've heard they tell about three separate - not
connected - "stories". Because of this, I didn't pick up
`Foundation' series by Asimov.

Second of all, while its literary style is amazing (and finding
out meanings of words is rewarding in itself, especially when
English is not your first language), storyline is pretty
straightforward, ideas not fully developed (unlike in Stanislaw
Lem), and narration very simple (unlike in Faulkner).

I might be wrong about straightforward storyline in `Solar Cycle'
books, maybe there is more depth in the story than I realize
yet (which would be awesome), but I doubt it...

By complex storyline I mean something more than mere `surprise'
factor, or trick techniques like constant change of time line,
point of views, heroes with amnesia etc. (in fact I hate these
and it's good that Gene Wolfe doesn't do that).

Today a massive solar from nowhere fries all electronics on earth . People are shocked but then the sky becomes brighter than day all around the world. The Great One whoever you believe it to be shows up once again and addresses the world ." I am displeased . My message to you however you interpreted it was for harmony with your fellow human . Instead you create new ways to exploit each other . I gave you a world of plenty for all but yet you squander it's resources for the few . You use my name for control and hate over your fellow human . For this you all deserve death . Last time I flooded the earth to destroy the wicked . This time you will destroy each other . I require each person to kill three people as your tribute to me . After this culling of the human race I will
again instruct you to live in harmony with your fellow human...YOU HAVE 1 YEAR TIL I RETURN...DAMN YOU ALL " What would you do? What would the world look like in a year ? I have written this book and am in the process of tweaking it. Would you read this . I have to warn you the story is horrific ! Not your typical one hero conquers all and finds love in the process story. It is humanity at it's lowest...and finest... Would you read something like this?

This is hardly like anything I tried to describe. Literary style
brings to mind biblical pathos (obviously), which in turn reminds me
of works by Roger Zelazny on the `good' side of spectrum, and Paulo
Coelho on the extreme low side.

If it's meant to be an epic book series -- it's hard to judge just
from this excerpt. Actually any book that could be approximated
this easily would be a dull read.

Good luck with your book, but that's not what I'm looking for.

Not really a "novel", but i found Urantia fun

Warrior Cats. The series has 24 books, not even counting special editions and whatnot, so dont expect to run out of things to read any time soon

check out the Dune series

You have no idea what Gene Wolfe is doing, lol

It's not at all a straightforward story. You might end up hating it though, IDK

Dune's cool