If you decided that you want to go with AT&T network sim, H2O wireless would be great option. They just raised their $65 plan to 8GB of data which is a lot. It used to be 4GB and now it's doubled.
H2O Wireless is a virtual provider that are using AT&T network and their service is stronger in airports and hotels. Also, not any GSM device is supported by T-Mobile so this is a great option for you.
Now you also get $20 credit for international calls and regardless you can call to more than 50 countries around the world to landline destinations only (No cellphones/Mobile destinations)
Net10 are also using AT&T network, however, they give only 5GB for the $65 plan. With Net10 you won't get any international calls credit or international calls at all.