Here's my 2 cents (for whatever that's worth).

I'm not interested in switching tools-- especially to a newcomer unless there are some game changing significant advantages.

Cost of a tool is not too much of a factor one way or another as long as it's not subscription based. I understand the time I will have to invest in learning the tool to the significant level I need to is much more of a one-time cost than the typical cost of the tool. A monthly subscription model isn't appealing as I may go several months without ever using it. That said I do have several subscription based products, but they are all set at 1 year subscriptions (Adobe Creative Cloud, SketchUp, KeyShot, Unity).

I see no killer feature in Vectary which would make me prefer it over Blender or even SketchUp for that matter.

I've said it before...for myself, I need 3D programs in a couple different verticals:

1. Polys: SketchUp (working on transition to Blender)
2. NURBS: MoI (best for CAD, hard surface modelings, 3d printing, Industrial Design)
3. Topology: 3D Coat (also great for UV Mapping and voxelizing poly models)
4. Rendering: KeyShot and Unity
5. Surfacing: Substance Painter

For now, that's just about all the time I have bandwidth for. I would like to learn Marvelous Designer at some point, but again, just don't have the bandwidth.