Neatly side-stepping all the issues about defining 'best', for me there's simply no doubt - it's a monochrome image.

Mayfield Park, Sheffield, 1988ish. Ilford FP4

I've never sold a single copy of it. It's technically flawed - without a tripod I couldn't hold the background clearly enough when focussing on the nearest bench (where I wanted the sharpest plane to be) at the slowest speed I could safely shoot at, and so I focussed further into the scene that I would have wanted. I have to print the neg on a harder grade than is ideal just to fool the eye into thinking the whole thing is sharper than it really is. But with a fair bit of judicious dodging and burning, the end result is the only picture I've ever taken which everyone I've ever show it to seems to like. Every other picture I show there will be some who don't like it, but about this one there never seems to be any disagreement. So in those terms, I consider it to be my 'best'. It's certainly my own personal favourite.