That’s a difficult question to answer, and I doubt you’ll find an unbiased comparison. At a high level I think you’ll find they’re quite similar functionality wise. Similar hardware support, simulation options, etc. At one point PX4 supported more VTOL configurations (https://dev.px4.io/airframes-vtol.html), but they may have changed.
Many PX4 developers will tell you they prefer the architecture of PX4 (https://dev.px4.io/concept-architecture.html), but we’re obviously biased. Another difference that may be important to you is the licensing of each project.
You might need more than 6 PWM channels (pixracer) to implement that Joby Lotus design.
Gitter is also a good place if you have PX4 questions. https://gitter.im/PX4/VTOL
I’d also recommend you try Gazebo simulations. You can simulate a VTOL including transitions.
https://dev.px4.io/simulation-gazebo.html