Seeking data vendors tracking private companies

I am seeking the group's advice on how to obtain data about private companies. As background, I run a merchant bank that specializes in working with private equity funds to source private companies in need of external capital. We are now researching data tools to aid us in our work, including data providers of company data (e.g., Capital IQ); sales leads and business intelligence (e.g., Salesfuel); as well as vendors who specialize in data scraping technology (e.g., InfoNGen). We are building a comprehensive vendor database including the data points that each of them collect, as well as information on their price and accuracy. We're interested in all data available, as each additional data point allows us to have additional insight into a firm. For example, we're interested in such data as: CEO age, degree of industry consolidation, corporate growth rate, industry growth rate. We’re also interested in data on public companies, but that’s less critical. Has anyone created a buyer's guide of the major data vendors and their strengths/weaknesses? If you know anyone who recently signed a large data contract with a data provider in this space, I'd love to talk with them, as such a customer likely completed an analysis of the different vendors. Also, we would be very interested in your feedback on leading private company data providers as well as those to avoid. Among the issues we're considering: format of data, method to download, and of course cost. Thank you.