Virtual PBX Suggestions

Currently using Grasshopper.com.  Is anyone using a different service that they prefer?  If so, what do you prefer about the service you use?

We just switched our two business lines to Vonage and saved 53% of landline phone bills (comparing to AT&T we had).  I did a little research and chose Vonage based on its reputation.  Price wise, there is not much difference.  Best Wishes!