If you wonder what tools are being used by technical communication experts, check out Technical Writing Tools: The Ultimate Expert Choice. The author, Ferry Vermeulen, has collected the favorite tools of more than 70 industry experts, including XML Press authors Rahel Bailie, Noz Urbina, and Richard Hamilton.
The article includes a summary of the most frequently cited tools, a list topped by MadCap Flare, DITA, and Oxygen. Well worth checking out, and the author invites you to add your choices in the comments.