You'd be better served to ask such things on a programming forum.
Do you know
wxWidgets?
This is a C++ UI SDK that targets Windows, Mac (both Desktop and Phone), and Linux. They are working on Android support, and also have I think some support for Database and networking. It's free.
I don't know Marmalade but I'm really not finding anything impressive in their applications. Smallish handy games mostly. Neither do I find detailed technicals. I think it's a fairly expensive way of creating what is basically browser games.
Also, take a look at the job market. That may be more important than technical considerations what you can run where.
Most chances you have currently with Java and .NET. But don't take my word for it, look yourself.