I\'m like many others here, giving their first steps in the mobile world an not knowing where to start from...
Well, I\'ve seen a few posts here about mobile developmen
I would highly recommend the Corona SDK.
Not only is it the easiest to learn (Lua is one of the most simple, and powerful scripting languages I've ever seen), but it also provides an extremely wide range of functionality in comparison with other third-party SDK's.
Development time is drastically reduced using Corona because most things only take a few lines of code to implement. There are also several monetization options available to you using the Corona platform.
Not only that, but it produces NATIVE apps, and allows you to re-use the same code to output for both iOS, Android, Nook, and obviously other platforms in the future. And that's the way cross platform should be in my opinion.
Performance is amazing, as well. It's strange because although Corona is the simplest to use and the easiest to learn, it's probably the most powerful among other options in terms of on-device performance, and the closest you'll get to going native without going native at all.
Another great thing is, you don't even have to touch Xcode or any of Android's tools--apart from installing them. With a minor exception of Android, where you'll need to use ADB to install the apk to your device.
HUGE BONUS: Support is excellent. The founders are very transparent, easy to get ahold of, and communication is awesome.
You can read two separate reviews I did on the Corona SDK, both were written six months apart:
--
Corona SDK Review
http://jonbeebe.net/post/1119939987/corona-sdk-review
--
Corona SDK: Revisited:
http://jonbeebe.net/post/2726165170/corona-sdk-revisited
You can do a search on my blog on 'Ted Patrick' to find an article written by Barne's & Noble's Chief Developer Evangelist for NOOK where he explains Corona's internal infrastructure and how well it works. I would post the link here, but I can only post two links per stackoverflow's policies.
Hope that helps!