Two base functionalities:
1) taking web fragments:
- saving that fragment (fultext-searchable) with formating and included images
- saving meta information (URL, position of fragment in the web page, taking time, origin time if possible, some identification of my device, etc.)
- some means to attach my notices to this fragment
- ideally some means to highlight or mark some words/sentences inside that fragment
2) possibility of simultaneous saving bellow data (either as built-in function of that software or at least as some possibility to reach such functionality through scripting/plugin/macro/API/... ):
a) saving URL of the webpage (as in bookmarks)
b) saving source code of the webpage, including images and js/css/.. files (similar to "Save as..." function of browser)
c) saving complete raster or PDF view of the same webpage
d) if possible, saving print versions of points b) and c) - many webpages have diferently formated print version
e) if possible, asking of archiving that page on archive.org/web website (it is "Save Page Now" function there)
So, as easy, as I am now saving my bookmarks in the web browser, I would save all those data by one click ;-)
I suppose, that wanted software would have some sorting/classification/searching/tagging abilities, of course. And some printing abilities. And some exporting abilities (or at least possibility to manually browse and access saved data)
I prefer open source or freeware or licence payed one time (one payment forever, i.e. no periodic payments)
Preferred platforms: Windows/Linux/Android/OpenBSD