The best enclosure is one in which you are best able to maintain a safe and healthy environment for the chameleon, providing the correct temperature, humidity, etc.
This
may be a screen cage. It may be something else altogether.
In areas where there are significant temperature drops /changes, an all screen enclosure allows heat to escape too quickly, resulting in an unhealthy climate change. In areas where the ambient temp is generally low, the chameleon is forced to bask to warm up, but the only places to move to when warm enough are significantly colder, which is not a healthy gradient. Another reason NOT to use screen cages would be the difficulty in maintaining decent humidity levels, if the ambient humidity is very low. Screen cages also do not always easily support installation of branches, feedingcups, hanging plants etc. Screen also obscures visability and can block UVB.
The good news about screen cages is that it allows air flow. If you live in a climate that is relaitvely close to those needed by the chameleon, this is awesome. Many others will chime in that screen is the way to go, and it often (BUT NOT ALWAYS) is.
So I will talk about the benefits of my NONscreen cages.
I use wood framed cages, with pegboard (painted) sides and back, a coated wire screen (NOT dense screen, more like wide chicken wire, so the UVB light gets into the cage very well) tops, and plexi-glass doors. This has worked very well for me. These enclosures provide good airflow, ensure side-by-side cage occupants dont see each other, retains some heat so that there is an excellent temp gradient, retains some and humidity (but not too much), when misting the walls of the room behind the cage are not water damaged, I can install branches plants and feeding bowles anywhere I desire for the benefit of the chameleons.
I'm not the only one to come up with this idea:
http://www.chameleonnews.com/?page=article&id=62
Check out this entry in my blog for more enclosure information/sites/threads:
https://www.chameleonforums.com/blogs/sandrachameleon/82-enclosures-housing.html