There have been many office suites on the market, though still MS Office is the major one. I am adept at using any of them, and find that each has some excellent apps.
I am an Access guru, and have found that app to be extremely useful in bridging gaps between systems, and providing enhanced reporting. On one occasion, I have used it to front end an A/S 400 system, much like a mini-Cognos. It has great power, particularly in analyzing large amounts of data across multiple tables. Through its use I have learned VBA (Visual Basic for Access) to develop dynamic reports and custom GUIs. Excel has over the years improved in its capabilities with pivots and vlookups, but cannot handle situations where changes occur or complex queries; Access is the next step.
Working with startups and small organizations, one comes across Quickbooks or Simply Accounting. I have used both, and configured Quickbooks as a power user. These both are simple 'canned' accounting packages, and are low cost and basic. You get what you pay for. However, for small businesses, it is about all you need.
TaxPrep is an excellent software for tracking and compiling tax returns for companies of all sizes. It is able to assist in the completion of all the schedules, and tying them out.