Best cross platform mobile app

So I showed the app that I have been developing on the desktop to many people and they think we need to bring it to the masses on mobile devices.  My app has to heavily process data that could take forever to process on a mobile device and display it in tabular form.  This would be inefficient.  So the plan is to do all of the heavy processing on a mainframe every night at 3am.  Then, a mobile user would only need to download the processed data when the app opens instead of processing it on the device, and they could sort and filter the data using the application as they see fit.  This would make it much more responsive.

I will be the first to admit that I am not a very good programmer.  I do not have the skills or time to write an app in different languages for each device and to maintain them.  I need a platform that I can write once and it will work on iOS and Android on both phones and tablets.  The only prerequisites that I have is that I can skin buttons for a customized look, plays nicely with arrays, and is very good at displaying webcontent such as pages or Google Maps.

My first thought was Adobe AIR, because I am already familiar with that language so the learning curve for doing a mobile app would be low.  But this is an app that would have a life of at least 5-10 years, and I am just sooo uneasy about Adobe's commitment to AIR in the long term.  We may try to sell this to a bigger company for their clients and investors to use and I don't know if they would have a lot of confidence in Adobe Air either.  I just absolutely love the platform though.

I have done a little searching and options like PhoneGap seem to be getting a lot of attention, but I have read a lot of negatives about writing code that handles complex processes.  So for all of you mobile developers, which is the best/easiest/reliable cross platform program to develop an app for?  Thanks for your thoughts!