I find it depends on which dinosaur you have. Some dinosaurs have better health than others. If you have a Carno, I'd go for Recovery. But it's your choice, really.
I also find that the gun is the main killer, the dinosaur is the one who deserves all of the health and every possible implant that will make it near impossible to kill easily, where as the gun needs implants that will make you be able to kill prey and opponents quickly. However, as previously stated, it's your overall choice.
Armor prevents people from making you drain health quickly, and their skills (i think?) do not have any dangerous effects on you, unless used at a good time.
Recovery makes it easier to regain health, and it supports the Vitality implant. The only weakness a Recovery Implant truly has is going against an opponent or prey that is of higher level.
