I'd go with the PowerSun over the Solar Glo based on testing it has a wider beam which I like. The 100w should be mounted about 8-12'' above the basking area for optimal UVB output and the 160w should be mounted about 11-15'' above the basking area. You may need supplemental lighting (halogen flood light or CHE/heat projector) to achieve proper heat gradients across the tank when you have the MVB set at those heights (it depends on the setup and your readings). That's the downside of using the all-in-one model - the heat and UVB can't be controlled individually with the one light.