The greatest tragedies are often the conflict between completely acceptable powers, not good and evil.

Yeah, that's a really good takeaway from this kinda of history.

Sun Quan was the weakest of the three leaders though. So indicisive!

In terms of individuality and becoming emperor of all of China, perhaps. He had a surprising number of really competent aides and generals, when compared to Cao Cao and Liu Bei. He was the kind of leader that was much more of a skilled manager of capable talent than a director who knew exactly what commands to give. In the long term, tho, this admittedly lead to politicking and infighting that cause Eastern Wu to rollover and die.

Also, it's worth considering that he was also arguably the most important of the three for their legacy. The Southeastern part of China is incredibly important /influencial in later chinese history, from Tang to Song to Ming and all the way to today, and Sun Quan had the unenviable task of fully absorbing the distinct jiangnan and southern chinese customs and idiosyncrasies into what we nowadays think of as chinese culture.