Luma versus spectrabox: its easier if you drop some links to the actual lights youre looking at, rather than just brands.
Looking around on whats online about these two brands: cant actually find a spectrabox web page, it seems like the next best thing is a dutch site distributing them. Also found some spectrabox lights on a china web, one of these alibaba/wish/aliexpress lookalikes. The Dutch site doesnt give too much info on what diode they use (they give 2835, .5W whites but not brand or bin), diode count or info on driver. It really looks like a droppship light which makes me a bit suspicious about trusting their 2.8par efficiency. So many sites will just quote what the chinese manufacturer quoted to them rather than do tests by themselves. When even some more name chinabrands tend to come in lower than quoted when tested my guess is that this will be the case aswell on an offbrand china light. Unless spectrabox specs can be confirmed by outside tests my vote is going to be for lumatech which is a name brand with a long history, even since hps days. Also ive seen plenty users around the web and i cant remember any complainers really, or any users whove felt stitched up by faults or bad aftersales cover.