Open Web Analytics

OWA's interface is much more professional.

Piwik's codebase appears to be a lot more stable.

Goals in Piwik are pretty basic: for example, you can define a page that triggers a goal, but not a funnel like you can in OWA.

It's easy enough to trigger a custom action in Piwik (e.g. logged when someone clicks on a PayPal button - just add an onclick="log me code"), but the display leads a lot to be desired. OWA seems much more polished in this regard.

OWA apparently has click heat maps, something that Piwik lacks, but I'm still trying to find them in the interface ;)

Those are my initial impressions. In short: OWA has the features, but Piwik's code is stabler.

http://www.openwebanalytics.com/?page_id=158

I'd be most concerned with scaling. Piwik doesn't really scale off a single server. Open Web Analytics lets you distribute the recording and queueing of events across multiple servers, but you still have to process stats on a single server.

I'd stick with a hosted solution for any high-volume project - it'll be cheaper in the long run. I'd only make an exception if you need a feature that the hosted solutions don't offer, in which case it's probably time to suck it up and start building your own analytics.

There is certainly room for open-source analytics designed with scalability in mind - perhaps with something like Cloudera's Distribution for Hadoop as a backend.

It eventually recovered but I would definitely do some research and further configuration before running the package on a site with high traffic. One friend at a news site told me that they put Piwik on its own VPS before ditching it for performance issues.

Whatever you decide to do, I would run in parallel a backup system from a proven and trusted provider — I scrambled to do so with Google Analytics once Piwik died.

:)