I've spent most of today online in various conferences, which has allowed me to make some interesting comparisons.
This morning I was in a Google+ Hangout discussing arrangements for #GEUG12, the Google Apps for Education European User Group meeting next month (places still available ;-)
The Hangout started started effortlessly as a native HTML5 application in the browser, and 10 of us chatted happily, sharing links and screens for an hour or so.
At lunchtime, I was due to join ALT's Rough Guide to Google Analytics session via Blackboard Collaborate. In contrast to the Hangout, I couldn't get the Collaborate Java file to open in spite of having used Collaborate before, and I missed the start of the session. Dan Barker did an excellent job of attempting to explain the complexities of Google Analytics in one hour, much more suitable in an academic context than Google's own commercially-oriented Answers To Your Burning Google Analytics Questions, but the sound was poor and the whole experience less satisfying than the Google Hangout. One advantage that Blackboard Collaborate has is being able to distribute a URL for a session in advance rather than having to do it live during the event or as a recording after the event. Other than that, I know which platform I prefer these days.
Which isn't Skype (any more), borne out by the fact that the person who was going to call me after the Collaborate session couldn't get Skype to work, so wound up phoning my on the old fashioned landline. How quaint.