Stop using mobile data and move to a talk/text only plan. These can be had for $10-$20/line - compared to $50-$60 dollars per line for a plan with data.
For those of you who aren't ready to do that, read on...
The big three carriers (TMO, VZW, ATT) charge a lot of money for their products. Many of the smaller companies that resell coverage on the big three networks (MVNOs) like Tello or Mint offer much cheaper plans but they suffer from de-prioritization: their users' data traffic is set to a lower priority than the postpaid subscribers on the parent network so it ends up being slow. There are currently only two MVNOs that offer full priority data relative to their parent networks: US Mobile Warp 5G, and Google Fi. Google Fi runs on the T-Mobile network, now that Sprint is a part of T-Mobile and US Cellular has backed out of their agreement with Google Fi. US Mobile Warp 5G runs on the Verizon network. They also offer another option called 5G GSM that runs on T-Mobile but that one is de-prioritized. They have a tool on their website to see if your phone is compatible with their Warp 5G (Verizon) network. Both services offer cheaper alternatives to the big three with no tradeoff in data priority. Of course that could always change. Here is a link to a Reddit post that keeps track of what is de-prioritized and what is not: https://www.reddit.com/r/NoContract/comments/oaophe/data_prioritization_policies_of_the_carriers_and/
Cellphone data plans
For those of you who aren't ready to do that, read on...
The big three carriers (TMO, VZW, ATT) charge a lot of money for their products. Many of the smaller companies that resell coverage on the big three networks (MVNOs) like Tello or Mint offer much cheaper plans but they suffer from de-prioritization: their users' data traffic is set to a lower priority than the postpaid subscribers on the parent network so it ends up being slow.
There are currently only two MVNOs that offer full priority data relative to their parent networks: US Mobile Warp 5G, and Google Fi.
Google Fi runs on the T-Mobile network, now that Sprint is a part of T-Mobile and US Cellular has backed out of their agreement with Google Fi.
US Mobile Warp 5G runs on the Verizon network. They also offer another option called 5G GSM that runs on T-Mobile but that one is de-prioritized. They have a tool on their website to see if your phone is compatible with their Warp 5G (Verizon) network.
Both services offer cheaper alternatives to the big three with no tradeoff in data priority. Of course that could always change. Here is a link to a Reddit post that keeps track of what is de-prioritized and what is not: https://www.reddit.com/r/NoContract/comments/oaophe/data_prioritization_policies_of_the_carriers_and/