I am about half-done the Wheel of Times book series by Robert Jordan, and completed by Brandon Sanderson.
I am taking a little break from The Wheel of Time (whose name should have been Prophecies of the Dragon, or The Karatheon Cycle instead) to read two Walking Dead collections (8 and 9 in hardcover); as well as some Zelda manga.
Anyway, while reading Book 5 and some of Book 6, I kept thinking 'This is the perfect series to own as ebooks!' I was thinking of more of convenience of the ebook format. Sure the new trade paperback editions are quite attractive, but at 14 books long, each of which is about 700 pages + (in mass market), there is no better series which is 'convenient' to have as digital files, rather than books.
George R.R. Martin's A Song of Ice and Fire series is smaller in physical size - it's incomplete at this moment, but will most likely be 7 books [at the time of this post. If George needs an 8th, it's because Book Seven became too physically large to bind as one book]. Sure some of the Ice and Fire books are huge, but it will never be as lengthy as The Wheel of Time to tell its story. While all of George's books exist in ebook form thus far, The Wheel of Time books were among the 'popular' books when ebooks began to emerge, or began to become popular.
From Book 9 through till the end of the series, the prologue (and a few sample chapters depending on which book) were released a few months ahead of the full novel, as an ebook. So The Wheel of Time became the first 'big' book to take advantage of the format. And reading a big book (series) on an ereader is far convenient. For new readers, I recommend either reading the series as an ebook, or get the new trade paperback editions if you prefer 'books'.
Taking advantage of the ebook format continues. Let's look Brandon Sanderson, the author who completed the Wheel of Time. A lot of his work exists in both physical and digital form, though he has released some novellas and 'bonuses' digitally, making an ereader ideal if you're a fan of his work. That, and his new Stormlight series (at this time projected at being 10 books) consisting of large books so far, it seems that that would be the next long-running series to own as an ebook. The first book, Way of Kings, came out a few years ago so it's a new series which could work really well on the ereader format.
I myself don't like 'mass market paperbacks' (I use ebooks in their place), so Stormlight will become my first series to own as ebooks. Plus, with my computer savvy know-how, any free samples Sanderson posts on his site legally, I can put them in a text document and convert it to the ereader file extension, allowing me to read that content on my ereader rather than on my computer.
So some long running series benefit on ereaders (unless of course you prefer actualy physical books).
I myself recommend ebooks in place of 'mass market paperbacks'. For The Wheel of Time, however?
Ebook or the new trade editions.
But then again, if there is ever a Wheel of Time omnibus edition, the ebook format would be ideal, as it would be one file.