I think like many on the gaming side my first contact with 40K was Dawn of War. That lead me to fluff wikis and from there to the novels. The tabletop gaming aspect always seemed too time consuming and expensive (and lack of artistic ability). So I concentrated on fluff and video games.
So I read many of the popular series like Gaunts Ghosts, Eisenhorn, Ravenor, Ciaphas Cain, Grey Knights, Spacewolfs and the Horus Heresy etc and played the Relic games. I liked most of them and was pretty high on GW/Black Library. And then seemingly simultaneously THQ shit the bed and Black Library really began to nickle and dime their readers, especially the Horus Heresy crowd.
More and more novellas, short stories and audio dramas were released, later to be collected in the main series (with wildy varying timeframe. e.g. the first novella Promethean Sun was just collected last year, seven years after its original release). The series was originally directly released in the small and cheap mass paperback version, which I liked, because it was easier to carry around and read for my commute. But after a while they decided to first release a hardback version, then a paperback and lastly the mass paperback. Since the last version was the most convenient and I didn't want to change the form factor of my collection over 20 books in (the cheaper price is a factor too), I had to wait like 6-18 months from the hardcover release from that point forward.
On top of that two of my favourite series, Gaunt's Ghosts and Ciaphas Cain were put on ice for whatever reason.
All of this really soured me on GW and I kinda stopped following them and buying books.
Only recently with the resurrection of Guilliman and all the new fluff and a bunch of youtube lore videos did I get back into it and look what we have here? Two new Gaunt books and a new Cain book. That is a good start. Horus Heresy is still fucked but at least it seems like they are trying to put all the side stories into the main book.