What is the best extension pack to display income statement, balance sheet and cash flow visually and with numbers .
Need sunburst chart , sankey that allows you to skip a dimension and allow negitive numbers (yes it is possible , i created one with d3 js), custom layout of the table for Financials.
The answer of what is "best" is really dependent on your needs and requirements are. In addition to native Qlik chart functionality there are extensions available on GitHub as well as several options provided through Qlik Partners.
This page could serve as a starting point to track down some extensions that might fit your requirements: https://developer.qlik.com/garden.
