LastPass, Dashlane, and I imagine any other password management services also encrypt your data, but since their software is closed source it can't be audited by third parties, we simply have to take their word for it that their encryption is strong and that there are no security flaws.

You also become reliant on their services, which is an issue if they suffer a server outage or the company goes out of business.  With Keepass, you don't have to rely on the company staying in business to maintain your password management software.

Lastpass and Dashlane are both great companies and are far more secure than using the same password for multiple sites or trying to remember a plethora of unique passwords, but Keepass, in my opinion, works just as well and has additional security advantages over the commercial products.