The UVB wattage won't make much difference in heat but it does make a difference in UVB output. How far above the main basking area are you planning to have the
UVB light sit? That distance will determine which one is best for your tank.
The basking light is a heat and bright white light and will need to be adjusted based on the surface temperatures it's producing. Different wattages will produce different levels of heat so you may need to do some testing to find the right fit. Having an adjustable lamp stand that allows you to raise/lower the bulb helps to adjust the temperature. I like to keep the basking bulb at least 12'' above the basking area and favor higher wattage bulbs at a further distance.