Although I don't use it anymore since I've changed jobs, for me it would be Appian. For people not familiar with it checkout my description in this comment http

Although I don't use it anymore since I've changed jobs, for me it would be Appian. For people not familiar with it checkout my description in this comment https://news.ycombinator.com/item?id=23583081 https://news.ycombinator.com/item?id=23583081 Beyond it's shortcomings it's something I'd gladly pay for (if I needed it of course) because it can't really be replaced by something free / opensource.