I'd be lying if I said aesthetics weren't part of it. I'm sure some will call me shallow, but I'm a designer; I appreciate aesthetically-pleasing and well-made things. I haven't seen a Windows laptop that compares in those respects to my rMBP, and I certainly haven't seen one with a comparable display.
I haven't finished my morning coffee yet so I can't think of specifics, but in general, I feel like I work much more quickly in OS X than in Windows. I designed on Windows for a few years, so I definitely do have a frame of reference. For example, Alfred has shaved a considerable amount of time off my workflow by automating mundane and time-consuming tasks. As far as I'm aware, nothing like it exists for Windows.
I haven't finished my morning coffee yet so I can't think of specifics, but in general, I feel like I work much more quickly in OS X than in Windows. I designed on Windows for a few years, so I definitely do have a frame of reference. For example, Alfred has shaved a considerable amount of time off my workflow by automating mundane and time-consuming tasks. As far as I'm aware, nothing like it exists for Windows.