Which is the best spend management software available in the market?

I have a small business that's growing at a good pace. To manage the growing demand and the expenses, I am looking for a spend management software that can:

1. Provide a centralized repository of procurement and purchasing data
2. Manage corporate or procurement spend
3. Include rules and workflows to approve purchases and payments
4. Match purchase orders, supplier invoices, and payments
5. Compare procurement budgets with actual spending
6. Provide real-time reporting of spend transactions