How much area do you need to light? Would you consider your plants to be high (full sun), medium (bright shade), or low (deep shade/indoor) plants? High light plants may overwinter in medium light. Once you know how much light you need, that will probably decide for you the type of light to buy.

All of my herbs are full sun, and I'll probably only want to light an area about 5' x 2'.

That area would generally be a candidate for 4' fluorescent tubes. These work well even for high light plants if they are placed close to the plants. For taller plants such as yours (?) you may need to get a little bit extra light by using T5HO tubes, or perhaps using two sets of 4 T8 tubes angled over the plants.

You should be aiming for perhaps 15,000 lumens with good reflectors for overwintering without too much growth, 20,000 to as much as 30,000 lumens for good growth. I would suggest that you don't have a need for an HID lamp, since a 400W metal halide provides well over 30,000 lumens.