Java/Android is generally the easiest to program for. There is a reason most uni's teach java and use android as a teaching platform. As for WP7, I can't believe it will ever be as popular as that graph suggests. As someone who works for a mobile app development company, I can only see android becoming stronger and stronger. Business forecasts put the Amazon kindle tab platform (android) as being a big hit this christmas. If you really want write a mobile app for all platforms, html5 is probably the easiest cross platform system, since it can run either in a browser on all devices, or with an app wrapper. (As for the comment about IOS running java, don't bet on it)
I completely agree, The main idea was to make it OS Specific, I may take a break on WP7 To work on the android as Java is one of my main languages as for html5 I am looking in to it
If you're not going to use html5, or html5 boilerplate you should at least take a look at the project as they have a lot of good tips. http://html5boilerplate.com This post on stack overflow has some nice information in it. http://stackoverflow.com/questions/5063117/choosing-mobile-web-html5-framework Another popular framework that wasn't mentioned on the above SO post I thought I'd mention. (If you're going to use bootstrap for mobile devices, make sure you're using responsive) http://twitter.github.com/bootstrap As a side note, I would just like to mention that the HTML5 specification is still a Working Draft. Not all browsers implement HTML5 and CSS3 fully or have the same features implemented. And just to make life more interesting, some people still enjoy using IE 6 and in my opinion, anyone who still uses IE 6 is a masochist.
