What other equipment do you use and why?
There are two other bits of kit that are absolutely indispensable for the kind of photography I do. The first is a good tripod. This is critical for getting sharp shots, blurring water motion, doing long exposures, and for consistency. The tripod is an amazing, but often overlooked tool.
The second item is a set of good filters: a CPL, a 10- and 6-stop ND, and sometimes a 3-stop soft grad.