Here are two resources:
For reading manga, one of the most affordable and good options is ReadManga.me. There are always fresh updates and new chapters, you can also create an account, rate manga, write comments and reviews.
DrawnStories.ru for reading ordinary comics.
СomicRack (both free and full versions) is the most reliable option. looks not very attractive, but works like clockwork
Astonishing Comic Reader - looks good, but covers are often duplicated, sometimes stupid and / or crashes
CDisplayEx - looks good, works well. no complaints yet
tachiyomi is a cool manga reader (offline / online), just recently came across. very cute
AniLabX is an application for reading manga, watching anime, dramas at the same time. multifunctional, beautiful. the main disadvantage is that in all these libraries, plugins, presets, etc., it's fucking hard to figure it out (or I'm just stupid)
if you also need to suggest sites, write