Leadwers engine?

Here is another possibility: Just stay with B3D. Then make sure you got a clean code with separated game and graphic logic. Most of the game logic should be outsourced for example to BriskVM-Scripts. And when the time is ready for a new 3D-Engine change to that language and engine you like.
(BriskVM supports B3D, BMax, PureBasic and C++, I think).