STL is very common in the 3D printing space, as many 3D printers accept it as their input file (to print with).
For other use cases, like transferring model data between programs, then STEP files (.STP) are very common instead. A STEP file contains much more data about the model than the equivalent STL file, so can be much more useful.
STEP seems like a pretty huge set of specs though (possibly a bit scary to implement from the ground up):
