I would just run one until you get a good gauge on how the healing sub affects you. Two Healing subs could be a bit much. Each approach healing from a difference angle, so all are valid and encouraged to run at some point.
Limit Destroyer is more about dealing with self-limiting thoughts and beliefs, such as I am not good enough, I don’t deserve love, I am not worth much, I can never reach goals in life because…
Others are more encompassing on the mental and emotional side with blockages…
Rebirth has been updated to Phoenix Reborn with latest ZP tech and the New Subliminal Experience, so I would go with that, if you are prepared to take the plunge. It could be more intense and cause more recon than Regeneration.
It depends on what your personal aims are.
Read the product descriptions and see which resonates with you most.