Snapedom

Perhaps these quotes will shed more light on what JKR thinks about when she's talking about considering bravery the highest virtue. And what, therefore, she most likely meant in having the final words of the book indicate Snape as the highest standard of that virtue. Remember, with this point I'm making, it's not what Harry is saying so much as what JKR *means* to convey that is important:

"I would want to be in Gryffindor and the reason I would want to be in Gryffindor is because I do prize courage in all its various ramifications. I value it more highly than any other virtue and by that I mean not just physical courage and flashy courage, but moral courage."

Now of course, many of us would immediately start wondering where exactly she found so much "moral" courage in Gryffindor. But the point I'm making isn't just that JKR thinks courage is important, but that she values it "more highly than any other virtue"! And further, that she means a courage that is not just physical (Bellatrix) or flashy, but "moral courage". So when she has Harry proclaim Snape as the penultimate example of courage -- especially when she makes such a point of this by giving this statement as the big supposedly surprise ending of the entire series -- I think you can bet that she didn't mean for Harry to be saying that Snape had the greatest "physical or flashy" courage, but the greatest "moral courage".

Now granted, if a reader isn't pretty well up on JKR's interviews, it's not terribly difficult to miss the point. But JKR almost certainly did intend the point of Snape's moral courage to be there.