I've been all Mac since about 2002, I believe. I use a 5K iMac on my desk and a Macbook for travel. For editor, I'm on TextMate 2. I only just switched from TextMate 1.5 a few months ago when an OS X update broke something in it. That editor was just perfect for me. Perhaps in part because I helped Allan Odgaard project manage and promote the very first version. I use both Chrome and Safari for browsing. I prefer Chrome for development due to the better inspector, but I prefer Safari for general browsing and native feel.
Besides that, I'd say that my most useful development tool on OS X is probably Dictionary.app. I constantly look up words and meanings in search of the perfect variable, method, and class names. (See here for a trip down that lane).
