Cant speak to any of them with regard to functionality or performance. I know they all have had issues needing to be addressed.
I've got a Rotorpixel on the way. I chose it, because it is expected to be upgraded to 3 axis later on, after they get caught up on sales. Additionally, the Rotorpixel is tranportable to other aircraft. It seems to be better made than their competitors.
Rotorpixel also made gimbals for the P2...So they atleast have some experience in gimbal design and performance... I do not know anything about the others, or if they have experience in this technology.
You'll need to study all of them to decide which is best for your needs both short and long term.
Good luck.