We use QuickBooks as an accounting program, and we also use a job package that goes along with it in order to track costs. We don't worry as much about cash flow. QuickBooks isn't user-friendly in my mind, but it's the most popular and well known. As an overall job-costing package, it has some limitations, but we work around it. Everything is on a spreadsheet and QuickBooks is tied to it. As costing goes in, we track it on an ongoing basis every time we get a bill.