I would be really grateful to have this "End" tag search implemented. This would help when I'm searching for manga to read and want to read it entirely in one go. Publication "Complete" is not really helpful here because it still can have only few chapters translated.
Also I have quite a lot titles in "on hold" or "plan to read" and if it would be possible to search in them for "End" this would allow me to create some simple script to check and send me email when it's time to read them. (or maybe you plan to implement some kind of "notify me when completely scanlated"?)
I would really, really, really love ability to filter mangas by rating. This is my biggest pain point with actual site. Like when searching or going to specific genre page hide all stuff with less than 7 stars (or even 7.5 starts if it's not too heavy on ES, I previously installed ES and even was doing some simple config/memory optimizations to it as part of my project but never actually run queries on it).