Expedition South/central America- gap year

Hi,

I've decided to take part in this expedition and volunteer work in conservation projects organised by this group (trekforce worldwide). I'll be spending 2-3 months in one of the following countries, which I've narrowed down to two places. Belize and Guatemala in Central America and Guyana in South America. However, I can't decide between the two i.e. which one I prefer to visit. The projects I'll be working on will be, to some extent, of the same sort, and the rainforests where I'll be trekking at are very similar, which makes it even more of a tougher choice. So it's more of 'what' I'll experience/see along the trek, since that is one of the few things that separate the two. And at the moment I'm leaning more towards Guyana. I've compiled a list of advantages of each location:

Belize and Guatemala:

- Natural Arch
- Chiquibul Chamber cave system and Victoria Peak
- Mayan ruins of Caracol
- Nohoch Ch'en sinkhole (depending which route is chosen)
- one of the largest coral reefs
- many exotic creatures

Guyana:

- it is almost completely covered by Amazon rainforest
- largest pristine and undisturbed rainforest in the world (according to Conservation International)
- home to the Cock-on-the-Rock birds (I'd love to see one)
- Kaieteur Falls, largest single-drop waterfall in the world
- Esquibo river
- only English speaking country in South America
- possibly has more animal/fish species since it's part of the Amazon

So, I'm really stuck between the two. As seen they each have their own advantages.

Another reason for making this thread is in hope that perhaps someone on here has visited one (or possibly both) of these countries and/or has taken part in one of the expeditions and projects organised by trekforce worldwide and could tell me a little bit about your experience. That would be really really great and appreciated. n_n Thank you in advance.