Putting aside coverage and speed differences between the two carriers, it basically comes down to whether you are looking to save money or spend more, but for more data. Both offer three different plans. On AT&T you have 250MB per month for $14.99, 3GB per month for $30 and 5GB per month for $50. On Verizon, the lowest you can get is 2GB for $30, then there’s 5GB for $50 and a whopping 10GB for $80.
Pricing is somewhat even: the two networks offer 5GB monthly for the same price. The only main difference is AT&T’s third option is on the low end while Verizon’s is on the high end. If you want a ton of data, go with Verizon, but if you are only looking to use a little bit at a time, AT&T might be the better choice. Then again, if you’re one of the majority customers to choose 2GB, 3GB, or 5GB, it comes down to coverage and speed.
As for deciding whether you should get the 4G model at all, there’s a bit of good news: it’s still contract-free. Turn on 3G/4G when you need it and turn it off when you don’t and you won’t be charged if you don’t use it. This is the way all tablets (and smartphones) should work, but alas we live in a greedy world.
Update: Verizon has clarified its 1GB plan is also available for $20 per month, a significantly better value than AT&T’s 250MB for $14.99. The mobile hotspot feature is available at no extra cost as well. AT&T has yet to comment on its own support for this, but it’s lookin like AT&T will not initially offer mobile hotspot with the iPad.