Android vs. Apple... Blah blah blah. IMHO, Apple is better in most ways, they just treat their developers like crap (speaking from experience). PhoneGap (i think) actually supports WebGL on iOS. Here's how they do it:
Apple allows WebGL in iAds, so it's there, just not accessible by the web because it's just "not secure" (http://blogs.technet.com/b/srd/archive/2011/06/16/webgl-considered-harmful.aspx). That being said, there is a way to hack through the wall keeping UIWebViews from using WebGL. Look here for more info: http://atnan.com/blog/2011/11/03/enabling-and-using-webgl-on-ios
And so that's how PhoneGap supports WebGL.
Here, you can enable WebGL on jailbroken iOS devices: