I am all along a Window user and have been doing web development on Windows for years. When I started work, all the guys in the engineering team are using Mac, so I thought I go with the flow and begin doing web development on a Mac. The experience was excellent, just need some time to get used to. After intensively using Mac for more than a month, I am proud to say, I am not going back to a Windows PC. My next computer shall be a Mac. I am hoping the 27″ iMac gets refreshed next year and it I am going to get that. Even Valve is bringing Steam to Mac. With Blizzard games able to run on Mac and Razer supporting it mice with Mac drivers. There is no reason for me to use a Windows PC anymore. If there is really a need (like testing website in IE), I will just use VMWare to run Windows 7.
Here are some software I use to do web development on Mac: