Not necessarily the most cost effective carrier for people who don't travel much internationally, but Project Fi is introducing a "Bill Protection [blog.google]
" feature that essentially gives single line users 15GB HS data for $80.
You still pay $20 for talk and text and $60 for 6GB of data, but Fi will stop charging you their $10/GB for up to 9GB more. After 15GB, you may be de-prioritized (soft
cap,) and can opt to resume paying $10/GB.
For multi-user lines, Bill Protection kicks in at $100 for two lines, $120 for three, $140 for four.