What is the best VOIP service between the UK and US?

Hi,
I wana move from the US to the UK and I need to know what would be the best VOIP system for my US friends and family to call me. l heard Skype is no longer the best one, any suggestion?
I wana move from the US to the UK and I need to know what would be the best VOIP system for my US friends and family to call me. l heard Skype is no longer the best one, any suggestion?