Depends on what you want. A 1000w will penetrate into a deeper, denser canopy. You could have a larger yield/plant.
The spacing is really too close for really bushy plants, so you'll need to keep them kind of small if they are bushy indica strain, start 12/12 pretty early. Thats why I recommend the lankier sativa plant with a deep penetrating light or probably better yet, the t5ho side lighting with a 400 or 600.
They grow really fast in this system. Good luck.