Out of the options, two 1000s, hands down. I went from a 600 to a 1000 in each of my 4.5x 4.5 tents. With the 600s I couldn't use the tents full height of width. I was flowering at 12" to keep my canopy short so I got full penetration and so I could keep them grouped tight together because light intensity dropped off allot at the edges With the 1000, I'm able to go into flower at 24", or more, without loss of penetration. Just about doubled my plants size, covered all the floor space and increased my yields by at least 75%. It's a no brainer, imo.
I'd go Led before HIDs if I was starting from scratch now.