I agree with potlike, 3 600w lights will be more efficient just because of the light distribution and the fact I can put them closer.

1000w lights have more lumens, but lose lumens per square foot by distance. 600w light can be put closer, making better use of the lumens they provide.

The cost between going with 3 600 per 2 1000w cant compare, I will be spending at least an extra few hundred on more ballasts, bulbs, and hoods.

I will have a complete seperate tent to veg, this is for flowering.

After a lot of research I think I may go with 2 7'11" x 7'11" darkrooms to flower. 4 600w lights in each.

This is going to totally blow my budget and cost about double, but I think I will be a lot happier with the extra space to flower.