MonoGame is stable and still receiving updates.

I would strongly suggest that for quick code-first prototypes. The boiler-plate of "load a texture and render to screen" is quite minimal - you could perhaps make a small library for yourself?

It also has no opinions about how you structure your game data. This means you can represent things like a Flappy Bird clone as just a `Vector2`, rather than having to bash a graph of entities in the shape you want.