I went HQI for the space issue, and the bulb color I wanted. Check out Sanjay's bulb tests and find the one you want.
HQI's are supposedly cheaper to run, but more expensive front-end-cost.
SE's on a Tar ballast are cheap to set up, but use more electricity.
Over time I think the costs are pretty close.
But, just like EVERYTHING in this hobby, pick one that suits your needs and go with it. Then half the people will tell you you've made the right choice, and half will tell you why you didn't!
B