What are some alternatives?
When comparing MasterpieceVR and Poly by Google, you can also consider the following products
Tilt Brush by Google - Paint in spaces around you with Virtual Reality
Vectary - Vectary is a free, online 3D modeling tool and sharing platform.
Oculus Medium - Sculpt, model and paint in virtual reality on a 3D canvas.
Poly API by Google - A free API for Poly. Development in 3D made simple.
VR Sketch - A tool for designers to draw inside virtual reality
threed.io - Generate custom 3D device mockups in your browser.