You know, I have been wondering the answer to that question for a few days now. I phrase it a little differently:

"What content deserves my reward?"

That is also coupled with the question of:

"Which content deserves my flag?"

For me, I answer number one with...
"Content that entertains me."
Now, I take that in a few different ways. I may be entertained by the post itself or the discussion it creates. In your case, you do usually end up with a good discussion...or multiple good discussions. I personally believe that some of your discussions could be better with a little more tolerance (just my opinion), but one thing that's hard to deny is that your discussions are, in fact, very entertaining. So you usually get my upvote.

Now for the other question...
I flag when I feel someone has been overpaid without any effort to entertain me or when they have copied the work of someone else. That's when I flag. I learned a while ago that whales will use their stake as they wish, and I will do the same.

In either case, I will also use my voice. Regardless of stake, I have a voice. I hold Steem. I study it. I contribute to efforts I feel make it a better investment. That means I am vocal and expressive about the issues I feel are important. that gets me into trouble here and there, but I know the stakes and accept them as they are.