4ch­an X (Also available on chröm):
Inline quotes (clicking on a quote will not direct you to the post itself, it will only expand it)
Backlinks (You can see who replied to which post)
Keybinds:
Close Options or QR
Quick spoiler
Open QR with post number inserted
Open QR without post number inserted
Submit post
Select next reply
Select previous reply
See next thread
See previous thread
Jump to the next page
Jump to the previous page
Jump to page 0
Open thread in current tab
Open thread in new tab
Expand thread
Watch thread
Hide thread
Expand selected image
Expand all images
Update now

Reveal Spoilers
Sauce (Add links to every post with a picture to search identical ones)
Thread expansion
Less bloat.

Nightly in general:
The ability to actually use all scripts proper (4ch­an filter for example)
The ability to use userstyles proper (Like Appchan)
Way more possibilities to configure everything (Even move a toolbar which is not possible in chröm)