Yes more lumens=better. Usually more wattage equals more lumens, but it also varies from bulb type. HID lights are great! Metal Halide and High Pressure Sodium bulbs provide great amounts of light for your plants, but increase the heat in your grow room. Heat can be controlled with exhaust fans, etc. You can still have a successful grow with CFLs though, but remember you are attempting to mimic the brightness of the sun for your plants to grow best, so more light will only lead to more growth. Unless you over do it, which is kinda hard unless your allowing your grow room to get too hot.