i have experience keeping in/on all three. and my experience was that free ranging is number one! the chams love it, and they tend to bloom personality wise. the only down fall is rigging everything up to work on a free range including misting/drippin, poop catching, and setting up the lighting just right so they cant mess with it or get to close. second up, is screen cages. they are just simply perfect for our use but slightly poor to the animals environment, though it is kept in mind that some would still rather the screen be there for their own hiding purposes which i have experienced also. lastly is ofourse the glass tank syndrome. for many of us in the colder regions, it seems almost necessary to have a complete closured environment to balance all of the so called levels of what we need to act on for their thriving purposes. but this is simply what needs to be done, just differently, in these environments. what i do is hand plastic up from the ceiling to floors in the area i want to use as my chameleon room, so that their space is segregated aay from the rest of the room. a black and white sheet plastic works well, keeping the white side in for reflection. i am soon to be free ranging 2 males inside of it on one side, seperated by a divider. and on the other side i will have 3 females in cages on a rack i made and mounted to the wall. draping off of the rack is a towel that nearly scathes the floor some 43-44 inches down, and hangs into a bucket full of water, placed neatley behind that is a space heater and small fan sitting right on the space heater taking the hot upward moving air into it and displacing it toward the towel. i get no more than a 1degreeF difference in the entire enclosed environment, and have perfect humidity. the basking lights during the day are enough alone to raise their temps to the perfect day time temps, and the space heater maintanes the exact night time temps. my enclosed environment is 4'x8', with 2 dual 4 foot fluro's(each with a reptisun5.0, and a 6,500k) and each chameleon has 1 40 watt house bulb for basking. i also keep my feeders in here and my crickets are hardy as can be! i hope this helps but other than some pygmy species no chameleons should really be kept in a glass or plexi cage at all. and if possible not even a screen cage, do FREE RANGE!