I have a pottery studio in my basement with a very large picture window(oxymoron- basement picture window, I know...)
My favorite thing about my studio is that it is all my space. It is like standing in my brain being surrounded by all the stuff that is me. All the stuff-images, sketches, notes from my son.... tacked to the bulletin boards, photos taped to the walls, and shelves of works in progress, my favorite jars of glazes, the clutter. Just like in my real life, when it gets cluttered, I can't work until it's put into some semblance of order.
As far as picking a favorite "thing", it's the wood work table my husband built for me a few years ago. It's solid!! I can wedge clay on it and it doesn't budge. It is 24 x60, and also has a lower shelf for storage. It is my primary working space after things come off the wheel.