Avoid the combo, and compacts for a cage your size, are you planting the enclosure with live plants? That's a major factor in your lighting configuration. On my 24"x24"s I use quad T'5s for UVB and plants plus a dome with basking bulb for species that need more than 80F. You want to provide gradients for the chameleon to choose its desired ranges for UVB, heat, and humidity. The dome bulbs concentrate all the heat and UVB into the same compact area not giving much coverage for a large 24"x24" cage.