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)