I'm using phone.com and so far am satisfied. I tried Ring Central last summer and it was okay, but I wasn't really happy that you cannot cancel your account online. You are forced to call them to cancel. I also didn't appreciate that they called me mid-way through my free trial who wanted to add something to my account but I couldn't really understand what she was referring to, so I told her to just leave my account alone. I had to tell her at least three times that I did NOT want whatever it was she was offering.

Keep in mind, even though you now have a specific number that may be printed on your biz cards, there are other services out there where you can transfer your number to a new service. Typically there is a fee associated with this (about $30) but it's at least an option if you are really unhappy with the service you have.