I use Google Fi + Visible in one phone and switch between the two as needed.
Fi: free international roaming in most countries, good tether speeds in urban areas in the US, 4 additional data SIMs at no cost for robots and other hardware projects that just use data from your main plan
Visible: better rural US coverage and fills in a lot of Fi's coverage gaps
Fi: free international roaming in most countries, good tether speeds in urban areas in the US, 4 additional data SIMs at no cost for robots and other hardware projects that just use data from your main plan
Visible: better rural US coverage and fills in a lot of Fi's coverage gaps