Well, zathura is great if you are a vim user, since it comes with all the key bindings and you can configure it like a lot of the tools out there with a dotfile. There's also support for djvu and other formats (although some distros do not have it by default, so you might need to compile it yourself). If you are not a vim user, you are gonna be disappointed, since its major feature is the vim thing imho.

That is nice for some users but again I feel like software including installation should be as easy as possible. We have actually lived in that era where we had to read documentation, install by compiling, and configure with dotfiles. I have had enough of it. I am happy with the basic functionality - read/fill form/annotate - that Okular provides in a dead simple interface and it comes with all format support pre-installed on all distributions that I have used. That's a win-win.