This question is a bit too open to address completely. What are the two "species" prevailing against? An asteroid hitting the planet? Simple uneventful life for the rest of eternity? There needs to be more criteria for me to have a solid vote on either side. However, in lieu of such information, it is my choice to vote for Humans.
I vote for humans mainly because we have a higher chance of surviving disasters. There are a couple points to consider with this in mind:
1. We know how to reproduce, communicate, learn, feed/energize ourselves innately. This means that we know how to do these things naturally. Of course, living in different environments changes our behaviour and knowledge level, e.g. people who live in the suburbs their whole life without camping MAY not have natural instincts on what food is appropriate to eat in the wild (what might kill you if you eat it) or how to hunt. However, in a disaster situation, we all come together as one unit and operate in ways we never have before for the sole purpose of survival.
A robot must be programed by something. Unless the creator of the robot teaches it how to do all the things we know how to do instinctually, then in a disaster a robot will continue to do whatever it does without batting an eye, presuming it has one.
2. A robot can easily be killed by an electromagnetic pulse. Yes, there are many things that can kill humans, but a lot of them can also kill robots. Robots cannot get a disease, but, like before, unless they are programmed to self-cure any virus or malfunctioning hardware, then they lose.
3. Power source. Robots need an input, and you can exactly find a power source input anywhere. Again, assuming a disaster situation, a robot would eventually need to plug itself in somewhere. Unless it is incredibly lucky and finds (assuming it knows how to find and recognize things) an entry to a building open and can access a plug inside it, then its days are numbered.
My whole argument hinges on the fact that a robot needs to be programmed to do something. With a robot, currently, there isn't any learning curve, at least not the type of learning we see in humans. It is true that there are robots out there being programmed with very sophisticated code that lets the robot learn, but what they learn is very limited, and mirrors things humans take for granted.
I will happily change my vote when robots reach the state to solve all the issues I have addressed (and no doubt I haven't mentioned plenty of other things that could be considered), but in the current state of affairs in the case of Robot VS Humans, I vote Humans. Remember, I'm talking current technology, not Matrix technology.
Also, if anything I typed up is false or inaccurate, do not hesitate to address it.