Studio lights are going to give you the most control and the most acurate color balance for sure. You can get all the cool accessories for them and most of them you can stop down to like at least 1/4 power.
I've worked with the halogen work lights your talking about and I've had a couple of problems with em.
1. They are whicked harsh up close. If your space is confined or you want a narrow throw you have to use a cloth in front of them.
2. They cast some strange shadows, esspecially the ones with the protective grate over the front, deffinatly get the ones with the removable grate if you go this route.
3. Your pretty much limited to using them for Fill lighting. You can get any sort of directional control out of the box and when you move them in close enough to cutt off the beams they get real bright.
All that beign said if your clever enough I'm sure that you could make a pretty decent studio setup using them. I have had great success using them from product shots in a light tent. I made a PVC frame and put a fitted bed sheet around it, then I place the 2 halogen lights outside the "tent" and the difuse glow that results on the inside is great for lighting products.