We had just come from Arenal and did ziplining with SkyTrek, so our experience was colored by the comparison. Original Canopy was highly recommended by our hotel keeper so we went with them. It was surprising what a different feeling it had, from the moment we walked into the office. At Sky in Arenal everything seemed new and ran like a well-oiled machine. Here, the office was old, rundown, with ancient lockers (only one of which had a lock), and barely a greeting. The equipment was old and worn as well--my finger was poking out one of my gloves. When we got to the platforms, they seemed rickety, especially the one for the Tarzan swing. I was more scared of the platforms than of the actual swing and ziplines! (The swing is super fun, though.) And once on the platforms, we were all huddled together awkwardly with not much space. Finally, the guides seemed a lot more casual. Our hotel keeper said they have a great safety record so this is really more about the impression they give than anything else. That said, it was still a lot of fun and the view of the Gulf of Nicoya is fantastic. Also, there were fewer people in our group here vs. Arenal, so we had less of a wait on the platforms. But if you only do one I'd personally pick Sky (at least in Arenal--didn't try them in Monteverde).