The new AT&T Unlimited Plan includes unlimited talk, text and data on 4 lines for $180 a month (after $220/month for the first two months.)
With this plan, you can also make unlimited calls from the U.S. to Canada and Mexico, and send unlimited texts to over 120 countries. On top of that you can talk, text and use data in Canada and Mexico with no roaming charges via the Roam North America feature that can be added for free.
Keep in mind that the new unlimited plan is not exactly unlimited. AT&T says that after 22GB of data usage, it may throttle down the speed during network congestion. Also the company omits the 10GB of mobile hotspot capability that the rest of the carriers are offering.
If you want to find out which carrier offers the best unlimited plan, here’s the detailed comparison.