Andy at VOIP Watch runs through a call test using quite a few players through soft and hard phone… Callvantage gets the confirmed flag with the best call clarity, followed by Vonage Voice Pulse and SkypeOut. I thought it was pretty interesting from his conversation, that Skype to Skype had a better sound quality to it than a SkypeOut call which used at least one landline, though he did not mention on which of the many VOIP services he received the call. I have a feeling it was Callvantage, and would bet there was no standard / traditional phone involved.
a multi-tasked stream of consciousness or perhaps just emails to myself
I called a cell phone at the other end of the line (I think). The best was as you noted CallVantage, and Vonage SF was better to the cell than Skype Out, but Skype to Skype was better than Vonage, and VP was well, suspect because of the drops.