I try not to, but can't help it, unfortunately. On the plus side: I see a lot of horrible writing, which makes me feel better about my own. On the other hand, I read a lot of stories from very talented authors, which makes me feel horrible about my much lower quality.
I very strongly agree with Erys, comparing yourself with others is not very useful, but comparing against your past self can be very helpful. That said, paying attention to the works of other authors can be very helpful as well, as that allows you more exposure to different styles and methods of doing things. You may even find interesting ideas you think you can do better, or at least in a way more fitting with your style.