It's difficult to truly answer this question because we don't see the most important part of the aerodynamics in this regulation set, which is the undertray/floor. With ground effect cars, most of the downforce is generated from the underside of the car.
That said, Red Bull utilize the area just above the floor to maximize downforce, almost similarly to the 'blown diffuser' concept that they maximized back in the Vettel domination days.
Ferrari's concept seems to maximize lowering the center of weight in the car. There is almost a bathtub-like look when you observe the car from overhead where the side pods push down and theoretically the air, at speed, increases that effect.
Mercedes went with what has been called a zero sidepod design. They claim that they can't run the car low enough to maximize the downforce potential with this design because porpoising takes over. Where Mercedes messed up, was not seeing porpoising in their wind tunnel testing prior to designing the W13 (or last year's car).
Toto's complaining about the ride height issue last year and forcing a new rule to raise the ride height may have actually hurt them even more, ultimately because they need to run the car low to maximize its potential. Because of the rule, I think we are going to see Mercedes abandon the zero sidepod concept pretty shortly.
What's interesting is, the Aston Martin is effectively a Frankenstein of all three concepts. Mercedes engine, gearbox, and suspension, which maximizes the strengths of that car which is traction. (Also this is a characteristic that Fernando really likes in his cars, dating back to the Renault third-spring days). The Aston also has the Ferrari downsloping sidepods from above, and the aggressive downslope on the floor like Red Bull.