What a great question, Sal, and I love each one of your items. They are winners for sure! That coat is one of my favourite pieces in your closet. So elegant and versatile.
It's fun seeing everyone else's picks, too!
I own a lot of classic or what I might call "classic adjacent" (i.e. trendy classic) items. But my oldest I think is the Hilary Radley knee length coat in cranberry -- bought in 2012 or 2013, at any rate in the year I joined YLF. I wore it yesterday! I probably wear it 10 times or fewer per year now, though when I first bought it, I wore it far more often. All in all, it has shown its value.
Most worn are probably the 3 J. Crew tux shirts below. The fit slimmer than most current shirts (less oversized, more classic), and they are made of gorgeous cotton that barely wrinkles. I got them maybe in 2014? Somewhere around there. Wearing them regularly, still, and they are still going strong.
A newer item that I hope will prove a keeper is tougher for me. I haven't shopped at all this fall, really! And my summer items tend not to fall into this category. So maybe I will pick my cashmere zip hoodie from last season, which has certainly paid for itself in CPW already, since I use it as loungewear *and* regular wear.