Three questions:
1.) If you had been a prominent Roman citizen at the time of Julius Caesar’s assassination, and the conspirators had approached you, would you have joined the conspiracy? Betrayed it? Or done nothing? Assume, for the sake of argument, that you have no knowledge of the future, and you genuinely care for the welfare of the Republic - you’re trying to make the right decision, not just the one that will best serve your own interests.
2.) Now, from a historical perspective - would Rome have been better off if Caesar survived? Would it still have transitioned into the Imperial system?
3.) Perhaps this is a fuzzier question, but - did Caesar deserve to be assassinated? Did his conduct in Rome’s civil war mark him out as a mad dog who needed to be put down, or were his hands no bloodier than those of most great men of his day?
Discuss! Debate!
My own answers:
1.) I would have betrayed the conspirators in a heartbeat, and cheered to see them on the cross. 
The last decades of the Roman Republic were a litany of civil war and economic crisis - the Republic simply didn’t work, from its bizarrely bifurcated consular system to the rapacious, chaotic gluttony of the proconsuls. A more ordered system was required, and Caesar set the stage for that.
2.) I think that, absent a strongman of Caesar’s talents, Rome would have collapsed within another few decades. The great thing about Caesar was that he had enough political and institutional savvy, unlike Sulla, to stay in power without spilling blood by the wagonload. Besides which - without Caesar, there could have been no Augustus, and there was a man who knew how to build stable institutions (which the Republic had sorely lacked). Without Caesar, I suspect we’d have seen a string of inept, bloody-minded strongmen like Sulla.
3.) Did Caesar have it coming? Heck, no - compared to Sulla, he was an angel among men. Even by more reasonable standards, it’s hard to point to anything he did and say “this merited death”.
