FWIW (probably not much) I've looked at both briefly, to build a tool with a 3d component. I know nothing about graphics (basically flunked it at uni) but Babyl

FWIW (probably not much) I've looked at both briefly, to build a tool with a 3d component. I know nothing about graphics (basically flunked it at uni) but Babylon seemed much more approachable than three for basic stuff (a box and a camera). However there is a lot more written about three than Babylon.