imo check Unreal Engine 4, it gives you much more power and freedom than UDK did. its Blueprint system (visual programming and object assembly) is fun, you have to go through some video tutorial series to get some practice, but the documentation is also improving. just subscribe for a month for 19USD/EUR. its development is awesome, there is always something to test, e.g. 4.7 is coming with a massive foliage rendering speed increase, which was not bad, produced higher FPS than 3DGS Pro in case of many vegetation models placed on a huge 4-testure terrain (under approx. 1000 trees 3DGS was better).

its C++ programming requires more programming skills, I could not start without spending the last few years of Lite-c and 3DGS! I'm experiencing with it sometimes, and now have a vision how to use it for my game (beside prototyping still with 3DGS).

and last but not least, probably you can find active team members easily in future (there are many 2D/3D artists).