Which sky map application for mobile devices have the best "feature satisfaction"-to-investment ratio?
I would like to have a comparison between "sky map" applications for mobile devices and it should be a factual comparison made by astronomy professionals, enthusiasts, and hobbyists. The result would be a user guideline on valuable applications.
I am always looking for great tools for amateur and professional astronomy to use for outdoor night observations.
(Tagging suggestion: this question can be part of a "How to make observation easier", subpart "mobile application".)