While there is a lot of drawings of GLaDOS here on deviantART, this one seems to really stick out. The coloring is almost perfect, you can see all of the effort placed into this. One of the details that is a personal favorite of mine is the wiring. I've seen a couple people skip drawing that part but The-Chook got them with every detail. The details of GLaDOS look like it was drawn by a professional. Although I think the paneled background could've used some more work (I feel like they're a bit uneven), this is one of the greatest Portal fanart I've seen on this site.