Android : I am Objective C expert , want to make apps for multiple platforms

I am Objective C developer , Now I also want to make apps for android as well. Suggest what should I have to learn from the following ? which is most appropriate ? * Android development * Xamarine Cross Platform * PhoneGap * Sencha Touch or any other. Thanks

I want to do Xamarine as it also supports windows Phone applications as well is it right for me ? Thanks