Julius Caesar has a lot of aspects that are easy to remember. His military career was an enormous success, his political ambitions were massive. He was good with the short quips, ("Alea iacta est", "Veni Vedi Vici"), and wrote about his campaigns, although these are more prosaic style. His assassination became the iconic symbol of betrayal, and the play by Shakespeare didn't hurt his fame.

Cicero, in contrast, was not a flashy military leader or head of state and died as an outlaw. His fame came from giving spectacular speeches, and writing letters, which made use of every literary device from alliteration to zeugma. (From time to time he would toss in some Greek phrases, the way that Latin phrases get used snootissimusly today.) His style of writing has been considered the gold standard of classical Latin language,

The thing about Cicero is that if he didn't like you, there was a fair chance that you would get dragged through the mud in one of his speeches, or at least mentioned in a letter. This might not be known by the modern layman, but is a very good contemp(t)oraneous quotable source, useful for making points in books such as SPQR.