Currently, there are couple way to make mobile app development.
A) Web based using Bootstrap
B) Native based using Android or iOS
This is pretty obvious but I'd just grab the most popular book on Amazon and go from there.
Recently, I've found that SenchaTouch (similar to solution A) that could be used as well. There is no such thing as best choice as that's relative from your expertise. I would go with A) since I just want to use what I know already.