There are several different types of plant lights that you can choose from. They will all provide lighting to your indoor garden, but each comes with different positive and negative characteristics that you'll have to weigh appropriately. The newest trend on the market is the LED grow light. While it is difficult to absolutely refer to one type as the best grow light, LED technology certainly makes a case for it.
Led lights are naturally very power efficient. This means that you can run them for long periods of time without having them make much of an impact on your electric utility bills. They still provide an excellent output of light for plant growing, although some people describe it as 'cold'. The efficiency is rooted in the fact that they produce very little heat. This is another great characteristic that sets them apart. You do not have to worry about the lights influencing the ambient temperature surrounding your plants and making the environment inconsistent.
Fluorescent plant lights used to be the mainstay of the grow light market. They have some flaws though that make them slightly less desirable. Although they are efficient like LED bulbs, they provide a constant flicker of lighting. The flicker is unavoidable although it is less noticeable at higher refresh rates. Nicer bulbs also solve the constant spectrum problem. A regular fluorescent light like you would see in a department store is not even close to producing the whole light spectrum, but the expensive models are much closer.
Other types include HID and incandescent bulbs. Incandescent light bulbs are really the scum of the light bulb world. They are inefficient, do not produce a good output, and have a really short lifespan. HID bulbs work really well and do not have the same problems, but have to be recycled when you need to be disposed of them.