Key features which make tracking enjoyable and powerful:
1. Intuitive and easy to use user interface. No redundancy
2. Add new records extremely fast
3. Handy widgets that could be used on lock screen
4. Multi-currency support
5. See your spending distribution on the nice and informative chart or get detailed information from the records list
6. Manage categories if defaults do not work for you
7. Be safely synchronized using your own Google Drive or Dropbox account
8. Backup and export data in one click
9. Use budget mode
10. Passcode protection
11. Multiple accounts support
12. Built-in calculator
Mint categorizes expenses from linked credit and debit cards, banks, brokerages, lenders etc and tracks them as per a budget you can customize. You get alerts if you exceed your budget limit & look at your overall cash flow to get a well rounded idea of your expenses. Mint is made by the same company that made QuickBooks and TurboTax as well.
Easy to set up and link your bank accounts. It helps track monthly income, bills and savings. The app also looks out for the best deals on recurring monthly costs such as phone/TV/internet bills.