Easiest way to clean up 26k photos?

I know some variation of this question has been asked, but none that fit my specific need.

I have 26k photos and 3k videos. I have already got rid of everything that isn't an image taken with an iPhone. These are legitimate images dating all the way back to my first iPhone, the iPhone 4S. There's tons of junk images (things like products/prices, multiple images of the same thing at different angles, etc) that I have never deleted. It's overwhelming to think of the task of cleaning it up and I neglect to do it, and it keeps growing. What tips, tricks, and apps have you used to manage your library?