If you're still open to experimentation, have you considered S&box? I've been really enjoying the process of learning with Godot, but I think I do eventually want to challenge myself to do a 3D project idea in S&box. Roblox doesn't really have a competitor right now, and I know many would argue that S&box's level of accessibility doesn't make it much of a competitor, but I think there is a lot of potential there.