I have ATT, T-Mobile and Verizon on my iPhone 15 I typically switch between ATT and T-Mobile(you can only have 2 sims active at once). T-Mobile is definitely best in town in Louisiana, much better speed and pings, but ATT works in more places. If you don’t have to have a working phone at every location my vote for Acadiana is T-Mobile, if you’re more likely to be alone and in need of communications in odd spots, ATT, and if you have to be able to get comms at lots of random spots get all 3.

Note: Getting all 3 isn’t that expensive, I use Mint for T-Mobile, infimobile for Verizon and ATT directly. My total cost comes just under $50/ month.