AT&T data speed is much faster than Verizon in the LA area. Yes, Verizon you will drop less calls than AT&T, but this does not apply.
Now, if the iPad 2 was capable of Verizon's LTE network that would be a whole different story.
I definitely recommend AT&T over Verizon. In Fact the AT&T version is very difficult to find in the LA area right now, because it could be used outside the country. Besides you get 2GB per month for $25 from AT&T and you get 2GB per month for $35 from Verizon. Also, if you go over on AT&T you pay $10 per GB.😉