I have tried all three of those. Anveo seems pretty flexible but oriented more toward business use. If you want even some of the simpler functions provided by Callcentric and
Voip.ms, you have to pay extra with Anveo and you have to be pretty savvy to set up their callflows. Callcentric has probably the best user interface [simplest] for the average user and if your usage is a little higher they may be cheaper in the long run than
Voip.ms because Callcentric offers "One price" packages. If your usage is not high
Voip.ms may be a little cheaper but not a whole lot. They only offer pay-as-you-go packages. As noted, both offer 911 service. Overall I believe Callcentric has the best customer service and I have contacted all three. One more thing, the Anveo pricing is very convoluted and hard to understand exactly what you are getting for your money.