Tally is a complete Enterprise Resource Planning system with a excellent grip in accounting features. Although it has many more core features that a business requires but its hold in accounting is truly commendable. Therefore it is known more for accounting rather than any other of its features.
If I have to mention a single software for a business need even if the business is just starting out, Tally is the one which I would recommend.
The reason for this recommendation is because Tally does all the things that a business at a time of starting up requires.
For example, if you are starting out a general store, what would you require?
1.    Accounting
2.    Billing
3.    Sales and profit analysis
4.    Banking
5.    Inventory
6.    Taxation (VAT, TDS, TCS)
I have brainstormed the needs of a newly opened general store which are all covered by Tally. There are more functions than this like Audit, Payroll, Manufacturing and so on which if needed can be used.
This was just an example of a general store and almost any business which requires a software for its functioning, Tally can be a best fit.