Independent. Strength. Honor. Integrity. The Senate is a lesser place today because of his passing as there is no one there, least of all Republican, who has any of those qualities.
As for the Keating Five, yes McCain exhibited poor judgement and sullied his honor. However, unlike many politicians he learned from it, and years later with Sen. Feingold passed a campaign reform bill 15 years ago. The flaw, later exposed, was that with the elimination of soft money you now had outside groups born after the United Citizens decision by the Supreme Court. Unfortunately there is now no one left in the Senate who would lead the reform against that. That era of reform Senators back around 2000 is now long gone with several having passed away.
May John rest in peace although I could probably say that he may have felt he was leaving too soon because of the perilous times we are in right now.