I've been thinking about this poll for a while now but finally decided to make it.
Personally, I believe Bigfoot does exist just because of all the evidence in his favor.
What you also have to consider is the evidence against, not just the evidence for.
Firstly, such a large creature would impact the environment. That is, there would be much more evidence other than a few random footprints that are dubious at best (and also that there is little similarity between many of the different footprints) and a few photos and videos (that again show a remarkable lack of similarity in the individuals shown).
If it is a predator, then you would be looking for Kill sights and impact on the existent predator species (a large predator would suppress the number of other predators in the area and this have never been observed). Also, it would have an impact on Prey species, which also has never been observed. This rules out BF as a predator species.
If it is a herbivore, then it would ahve an impact on vegetation. There is a minimum population size/density and for a creature as big as BF is (human sized) this would leave a very large impact on the surrounding vegetation (think about how much food a small village eats, and this would be the impact of a small group of like sized individuals).
Now, onto populations.
To avoid inbreeding, then a species that has a similar amount of offspring to humans would require a similar level of minimum population levels to avoid inbreeding. Now for Humans, this is, with careful genealogical record keeping, about 1000 individuals. Without, this careful intervention, it would be around 1500 to 3000 individuals.
So, any population of BF would have to be at least similar in size, but any population of this size of human sized creatures would make enough impact on the environment that iy would show up on aria photos. This has never been observed.
So the evidence that you would expect a population of BF to leave just is not there. One or two footprints might be acceptable for a small population of widely dispersed creatures, but even then there is a host of other ancillary evidence (eating habits, droppings, lairs/nests, etc) that just is not found.
Usually when these rare animals are found, they are usually unique (escaped animals), or inbreeding populations (or widely dispersed and long travelling creatures - like birds). A creature that has existed in the areas for hundreds of years can not be inbreeding (or they would have become extinct by now), and being human sized and shaped will not be long travelling).
The evidence against BF is far more than the evidence for it, and much of the evidence against BF rules it out regardless of the evidence for it as it conclusively states that it could not exist (it would have become extinct by now either through inbreeding or though the population being too dispersed so that mating would be impossible).
Poll