There are three types of VA tools. First are scanners, which give little beyond listing vulnerabilities, their relative importance and suggested remedies. These are very useful because they can be utilized easily, mostly automatically, and offer a good ongoing quality assessment.
The second type of tool is the full-featured appliance, which not only performs vulnerability scans, but correlates results to regulatory compliance, patch management and a host of other reporting functions.
Finally, we have the tool that does just what experienced pentesters do: scan and follow-up with penetration attempts. This tool behaves exactly as one would expect a hacker to behave. It scans for vulnerabilities and then attempts to penetrate.
Vendor: Tenable Network Security
Verdict: Excellent well-established product with strong community support.
Product: Auditor Enterprise
Verdict: Fully featured appliance tying assessment to auditing and compliance.
Product: Core Impact
Vendor: Core Security
Verdict: Superb pen testing tool going well beyond vulnerability assessment.
Product: Saint Scanner
Vendor: Saint Corp.
Verdict: Great scanner with a very good interface and established credentials.