In a 3x3, I'd be kind of tempted to go with two of the HLG 100 (if you are stuck on buying HLG) which cover 3x3 in veg, 2x2 in flower. With two lights covering that area, the benefit of overlap from the light sources will bring higher, more evenly distributed PAR numbers, but it also gives you the ability to have one light higher than the other incase you get a mix of tall and short plants. I generally like the modular approach to things. Personally, I do want a light with a dimmer on in though.