The best disses imo are the ones that analyze your career to the T. And that's what Jay-Z did. Few personals, mostly facts. the fact that Nas fell off. Look at Common's "The bytch in Yoo". The reason why it's one of the most vicious disses ever is that it plainly analyzes Cube's career.
"Hawaiin Sophie fame, kept my name in his music" which points to the fact that Jay was lying when he said he's been in the game since 96, as if his 89 rap career doesn't exist, as if he wasn't sampling or saying Nas name or quoting his lines
"KRS Already made an album called Blueprint" which points to Jay constantly recycling classic rap lines, ideas, which would continue with Bonnie and Cyde 03
"First Biggie's your man then you got the nerve to say you're better than Big" which points to Jay's obsession with telling people that he's better over and over, desperately wanting that narrative to stick
"You only concerned with dissing women" which points to Jay's long list of singles (including from his first album) about pimpish behavior (which even Jay would admit stemed from his insecurity of being called ugly, "Got on my pimp game, fukk the world, my defense came). Jay got comfortable with remaking this type of record over and over again, and ironically it went away after Ether was made, though that may have more to do with his relationship with Beyonce. But Jay did get defensive about it, which can clearly be heard in his Blueprint 2 response.
"Is he Dame Diddy - Oh I get it you Biggie and He's Puffy" which again points to Jay attempting to recycle what has worked for other artist
"Went from Jaz to hanging with Kane, to Irv, to Big" which again points to the idea of Jay wave riding others (which would continue with him rocking with Kanye even though it was Dame to put him on)
"You're a dikk riding fakkit, you love the attention" which has an entire thread on here filled with examples
"You pop shyt apologize" which would happen in this very battle
Ether was a scathing breakdown of Jay's career. Heavily slanted to only include negatives, sure, but this is a battle. Jay's most successful rebuke of Nas career was the "one hot album every ten years" line, which only looks silly in hindsight because nearly NO one considers IWW a meh album anymore. But people still do believe Jay got murdered on Renegade.
Ether holds up better when looking at "facts", especially since the things Nas said has continued to be true about Jay's career (even in 2016!)
Takeover did have the better beat and was still an excellent record. Too bad Superugly didn't have the same calculated nature to it.