By far the best I have found for my needs is Keepgo.com
It is $59USD for the sim and 1GB. Then 99USD for 3GB.
Roaming in 64 countries and growing. I have used them for about 6 months now and mainly use them for when I get off a plane to accomodation, stopovers, when I am ducking in and out of a country for a few days (ie not worth buying a local sim). I move a heap and have used 750mb in that time. I am actually sure I have used more than that but the system just seems fair and you don’t get these massive data shocks.
Anyway that is my 2 cents worth and cleary I am not using it for day to day work (ftp transfers/syncing large files) etc. More for emails, navigation, app downloads occasionally, and voice calls (Skype, WhatsApp, viber softphones).
Has an app to reload/manage data too.
Do your own research on it but If you are thinking of buying please use the link below which is a referral link. U get 15% off and I get some data.
To make it 100% clear this post is not to sway you to use my referral link and ‘all about me’. Keepgo is just an awesome service and if you are going to buy it, why not benefit someone in the community and get a discount yourself