Selling a newer laptop

My office literally gave me a Dell Inspiron 15Z, not just to use for work, but to keep. I'd be a huge asshole if I said I was ungrateful, but unfortunately our IT guy isn't really an IT guy, and he got me a refurb laptop - works perfectly well, but not amazing.

I actually needed a new laptop and I edit photos frequently in Lightroom, and while this thing can support programs processor wise, I really wanted to get myself a new Asus Zenbook infinity or the Acer S7. Now I'm sort of stuck with this laptop, handed to me for free, vs. spending a good amount on a new laptop.

Anyone know any good places to sell, besides craigslist? If I'm going to get something high end, I'm going to need to get this sold, and it's in perfect condition. Thoughts?