Comparing iPad mini data plans; Why choose AT&T, it has fewer countries and is more expensive? I'm trying to choose between the various data plans for an iPad Mini.  Based on this chart it appears that the ATT model (A1454) only works in North/South America, while model A1455 is supported worldwide.

For this reason (limitation) I assumed the ATT plan would be least expensive per MB/Month, however it is the most expensive per month:

  ATT       250MB per month $14.99
  SPRINT    300MB per month $14.99  (better value)
  Verizon     1GB per month $20.00  (best value)


What is the value in the ATT network or related technology that I'm missing?

Finally, I've been told that GSM operates worldwide, are both these models GSM or CDMA?
The value of any particular carrier is based on the performance of the carrier in the area you will use the device.

ie. My area has great AT&amp;T coverage, Good Verizon coverage and horrible Sprint coverage.

You are also only comparing the cheapest tier. Prices change and one carrier may be cheaper than another at a different level of service.