Just remember that with the other carriers their Unlimited Data may not be truly unlimited or may come with another caveat.
For example with TMobile it's only unlimited on their network. If you roam (which is much of the country, especially rural), you only get 50MB of data to use. After a few webpages your data will not work and you will need to go back on their network or use WIFI to be able to go online again.
Sprints is unlimited, but they are known to have horrid data speeds. To the point where Unlimited Data is pretty well useless.
And Straight Talk throttles you to 2G (barely faster than dial up) speeds once you go over 3GB of data.
So be aware that unlimited data may not be truly unlimited or may come with other caveats such as no unlimited data while roaming. Read the fine print and don't trust that the sales people are being honest with you.