I think which is better depends upon the environment that the cage is in. If the cage is indoors, than I agree that glass terrarium will hold humidity better and may be easier to deal with for lighting requirements. This might make it a better choice.

The idea of a custom terrarium,suggested in the previous post may be a good way to go.

If your lizard is in more of an outdoor arrangement than an all glass terrarium could dangerously over heat.

I happen to live in a humid, subtropic area in terms of weather. Majority of the time, I use an outdoor reptarium situated in a larger screen patio area. He gets a mixture of sun,shade,air and I keep careful watch on the humidity. I bring my lizard indoors if the temperature and weather aren't good.

Hope this is helps