I decided I want to ditch my cell plan and rely primarily on a VoIP service for calling. To anybody here have any experience with VoIP: what providers would you recommend?

So far the two that I see recommended the most online are JMP and VoIP.ms. I setup an account with VoIP.ms, but am hesitant to pull the trigger until I have done a little more research. Any insight and info would be most welcome.