First I think it should be obvious that cold hard scientific facts and mathematics about why this is better than that will not be procured from a bunch of pot heads on the forums growing weed in their closets... so anything you get is going to be "my shit grows fine" And honestly, that is the best way to decide what is the best... try it yourself and see the results first hand. At least as opposed to taking advice around here. That said... I have tried most of the popular stuff (except AN) and I think Dyna-Grow pro-tekt, grow, and bloom are the best for DWC, and botanicare cal/mag if needed.
Protekt because it is the most concentrated source of silica vs silica blast or rhino skin
Grow because it supplies all macro and micro nutes weed needs to veg. It's ph stable, concentrated compared to say GH Flora 3 part, cheap, no part A/B bullshit. Mineral and salt based which eliminates the need for biological processes converting elements and reduces the chance of a slime bloom. Time tested and proven in many different applications on many different scales.
Bloom for many of the same reasons as Grow, although it may be too hot in P for most strains in DWC.
Botanicare Cal/Mag because it is cheap, salt/mineral based, provides ph buffer, and DG Mag Pro does not contain Cal.
One I left out is beneficial microbes. For this I think Aquashield is the best, followed closely by pond-zyme based on the fact that I have never gotten slimed with these products when properly used. Pondzyme is cheap as dirt, but the barley can be annoying in 5 gallon DWC.