What is your favorite HID bulb, and why?

Good thing they really talk up PAR in these HID bulbs if we are talking HID grow bulbs its pretty obvious the PAR will be similar.. some might have a lil extra blue or extra red.. but when its all said and done.. the PAR for HID is pretty close across the board... otherwise HID descriptions would use PAR to differentiate between these bulbs... instead they use Initial Lumens... why? because lumens are a good way for us humans to rate these bulbs..

LED lighting is where the PAR ratings become more important

Thanks to everyone whose shared so far, especially Buzz I've been reading those articles and will play a little more with them but my computer took a shit on me so using a smart phone to view the garden sucks! Also thanks for the graphs kantana I'd never heard of the phillips retro bulb but will be looking now since I run 400w

Katana-looking at the graph, I would think the retro is not as good. Plants can use only very specific wavelengths of light, so having a large distribution is not really a good thing. Assuming two bulbs put out the same amount of light, but one has a very narrow spectrum of light that is in the range that the plant is most efficient at converting to energy, then the narrow spectrum bulb would be better. This is the reason LEDs are so good. They have a narrow spectrum and therefore less watts can be run, even though they put out less light per watt.