We've tried pretty much every XML tool out there. While Oxygen is undisputedly strong for XML "programming" (ie, XSLT transformations, etc.), we've found that it's not nearly as clean/easy to use as XML Editor for "exploring" XML docs. XML Editor's tree view is excellent. Also, it's $55 as compared to Oxygen's $225, which is 4x the price.

As well, we had a couple of questions/issues that we sent to the author. Not only did he reply within a day, but he actually programmed a handful of fixes and enhancements and sent a new build within a couple of days. Unbelievable responsiveness and customer service. Two thumbs up