There is one thing you should keep in mind before deciding on which one is best. Most hosted VoIP applications have the same features and about the same monthly/annual cost structure. Most will also provide a softphone (residing on your laptop) for your traveling needs.
The biggest determining factor in whether or not you will be happy with whoever you select is the Quality of Service issue and that is ultimately controlled by who your ISP is going to be and how well their network meshes with the VoIP provider's platform. This is a technical hinge not often considered by small businesses (or telecom consultants, for that matter). Go ahead and compare features and pricing, but only after you determine how well each option you're considering will mesh with whatever Internet line you'll be running it over. Hosted systems means you will be running things over the open Internet, not an MPLS (for example). This will ultimately be the deciding factor of what level of Quality of Service you get.
You definitely need to look beyond features and price points since most providers are very similar. Quality of Service (QoS) including the customer support piece .... as well as synching with your ISP are the real difference makers in a decision such as this.
That said .... of the many options available to you I recommend that you consider Packet8 (also known as 8X8) and Ring Central for your short list. Both meet the sniff test for features and price points .... and more than hold their own in those arenas. In fact I'd say they're both more than competitive. What sets them apart is the QoS aspect and ability to "play nice" with most any ISP. Even the lesser quality internet providers.
Packet8 has won numerous industry awards for their various business packages. They also are built around Uniden phones (top of the line hardware there) …. Plus they have video phones as an option if that's of interest.
My experience is that a hosted VOIP solution works best in a very small office, say four to twelve users but after twelve users the monthly expense starts going up and a premise based solution would cost you just about as much as a hosted solution.
The benefits of a hosted solution are obvious; smaller initial start up costs and many ‘big-boy’ features for the dollar. The problem is scalability, management, service and on-going costs. Another hidden cost is bandwidth. I have a customer that purchased a T1 of internet access and then purchased 25 phones from a hosted IP provider. The problem was when all of his agents were on the phone, there was no bandwidth left to access their hosted CRM. So now they needed to purchase another T1 to accommodate their Voice and Data traffic and BAM, there goes the ROI for hosted IP.
If you have a small office and a reliable internet connection, go for it. Otherwise I would recommend you look at a premise based solution.
Keep in mind ... again ... that ultimate quality rests with your ISP not your VoIP provider. Internet connectivity is the limiting factor ... what makes or breaks VoIP call quality and performance.
I suggest looking over the other Hosted VoIP Providers listed on the link provided below ... side by side with Packet8 and Ring Central (also listed) .... and decide from a fact based position. Just don't forget to test with your ISP for true compatibility and desired performance levels.
Hosted VoIP Phone System Providers