Mine was a new lens for my camera, a Fujifilm XF 35mm f/1.4.
It was for sale, so a good price, and I had researched online, liking the photos that I saw very much. Of course that is mainly the skill of the photographer, but I like the "slightly old fashioned" look of the 35/1.4 rendering and bokeh.
Besides, good glass keeps its value, so I prefer spending my money on that than on a new camera. Mine is a Fujifilm X-T1, which is already a few years old, but still delivers impressive images. I am convinced that a new lens has a much bigger impact on my photos than a newer generation camera.
So ... what did you buy, and why? How do you like it, and what do you expect from it? 🙂