Google Fi is the only provider that I know of to best protect against SIM swapping due to the fact that there is no human interface. An attacker would have to get control of you Google account in order to attack you—if this happens it is likely you have bigger issues than SIM swapping.
Given Jack Dorsey's recent Sim swapping experience coupled with countless cryptocurrency SIM swapping horror stories, it feels like Google Fi is necessary. The only negative thing I have heard about Google Fi is the requirement to pay per GB. This point is now moot.