[k_men]

Hi! Welcome to the forum!

Regarding your question, you're likely to get as many answers as Kobo/KOreader users.

My own experience drove me towards KOReader mainly because of its PDF reading capabilities. It can do a reflow of the PDF content, apply OCR using Tesseract datasets to allow any text to be searchable/selectable, and has a staggering amount of options.

Lately, I've taken up using KOReader as my main reading interface on all my ereaders (Kobo as well as Kindle). One reason is that i like having the same interface on all of these devices. Another is that I, for one, prefer not to share data on the books I read with a third party, be that Amazon or Rakuten. This might, or might not be important to you. But I'm a happy camper. And I have to say this is not related to Kobo's default, Nickel interface - I find it fantastic. It's just that KOreader gives me some extras.

At the same time, if you're a complete newbie as you say, you might not want to dive into installing third-party tools on your ereader just yet. My advice would be to evaluate what you needs and wants are, and, depending on how your reading devices satisfies them, proceed from there. If you look around the forum, you'll find that there are a gazillion ways to fine-tune your Kobo reading experience even without delving into the complexities of installing another reader on your device.

Going back to your specific questions, if you'r reading mainly (k)epubs, you might not see many substantial benefits from using KOReader as compared to Nickel, at least not at a first glance.

Nickel does a few things substantially better. One is its handling of collections and series via Calibre, which is just excellent. KOReader, by contrast, uses a mainly filesystem-based interface to your library. It can browse tags, but it has a rather clumsy interface for that. There's an option to add series to a book's title in the filesystem display, but that's about it regarding series. Another advantage of Nickel is its handling of DRM for books purchased through Kobo, borrowed from a library, or side-loaded via Adobe Digital Editions (KOReader doesn't handle DRM of any kind). It also has a very effective Pocket integration, if you use that - KOReader only allows integration with Wallabag, which is libre, but not as popular. Finally, I find that KOReader tends to consume more battery than the default interface, both on my Kobos and my Kindles. Not much more, but enough for me to notice.

Among the things KOReader does better are its seemingly infinite ways of adjusting page display, fonts, and other parameters. Its handling of user-defined dictionaries is also much easier than the stock one on Kobo, which is a bit of a mess. I also prefer its epub rendering in general (although that can be fine-tuned in both interfaces). It also has a nice, modular plugin API, and comes with a selection of plugins that add a lot of functionality: an RSS reader that downloads articles in epub format, an excellent OPDS interface, a very nice "Book Map" feature - a kind of "expanded" table of contents - and a very effective way to access your Calibre server if you use that feature of Calibre, and a highlight export feature which renders some very nice html files (Kobo highlight export depends a lot on a Calibre plugin, and is effective, but not as nice). Also, while not sharing reading data with a third party, it has an excellent reading statistics interface, with tons of report options.

Tl;dr: If you're just starting out, and you mostly read epubs, stick to the default Nickel interface. But do keep an eye on features and user feedback here on the forum and on the KOReader github. At some point, if there's anything you need that Nickel can't do for you, and there's no way to coerce it into doing it via config files, then KOReader might just be what you need.

Happy reading,

K.