Which LED Black Boxs

So I purchased 2 used black boxes off somebody used, and one of them is starting to go out. I got these just get started to see if I like the hobby.

Well now I want to get some new black boxes. They are pretty cheap and will hold me over as I learn and grow with the hobby. The question I have is what black box to get?

So two questions, I have a 75 gallon tank, 48 by 18 if I remember correctly. Right now I have two 16 boxes that are about 9 inches about the water,

1. If I got one 32 inch box will I hit most of by tank? SB reef light has a nice 32 inch LED light but it seems they say it needs to be 14 inches up for a 48 inch tank. Anybody have this set up? Hitting the outer edge full strength isn't a need.

2. If I go two lights (16 inch), for a beginner, is there really any different between Marsaqua, SB Reeflights and the other black box builders? I know some use better quality LED light but is it really worth the money for a beginner who is growing LPS, Softies?

Thanks for any input.