That depends on what you're trying to grow and what phase the plant is in. Certain plants are adapted to grow in the shade or in warm, sunny environments. Depending on the plant, one type of light may work better than another. For example, if your plant needs a shadier environment, then a regular incandescent bulb may work best.
The other factor that goes into choosing the right grow light is what phase your plant is at. For example, a high-pressure sodium bulb may be best when your plant is in the flowering or fruiting stage.
Personally, I love using LED grow lights
. Modern LED bulbs are more energy-efficient (they produce more light with less power), so they cost less in the long run. They also produce less heat, which means you don't have to worry about a ventilation system. Plus, they emit light wavelengths that correspond to the peak absorption peaks for most plants.
When choosing your bulb, you should look at the requirements of the
plant and how those requirements change as the plant continues to grow.
Keep in mind that the larger your plant gets, the more light it will
need, so plan ahead.