I think you'll be happy with Vonage, as long as they don't go under.
I used to use Skype as my business line, but unfortunately they don't provide caller ID service, and a lot of people I work with and customers that I called were screening their calls because the caller ID was coming up with '1234567' as the caller ID from my phone, and they dare not answer something so weird. It was also a bummer being tied to my PC with a headset, but I could have paid for a router that I could hook my normal line into, or bought a wi-fi phone, but never did. The caller ID thing was the main problem. Glad Vonage and other VoIP providers don't have that same problem.