There's some that are missing from your list which possibly deserve a mention ... JUCE, Corona and Moai. All of these support iOS and Android. Corona is mainly for games but is pushing into the general app area as well - and it has a very active community. Moai is mainly for games and interactive graphics. Moai and Corona are designed for Lua scripting. JUCE is an elegant and well structured C++ based cross platform UI library.
