Brett Ewins work is archetypal 2000AD imagery. It's future-punk anarchy. Love it, but I'm not voting against Cam Kennedy. As has been mentioned, Kennedy's future war stuff in Rogue Trooper and VCs really is top notch. Could he have done Bad Company as well as Ewins iconic effort? Yeah, I reckon he definitely could have. Ewins Rogue is very good (who can forget his version of Venus Bluegenes?), but not quite at Kennedy's level. I can't quite see a Kennedy version of Anderson Psi Division being better than Ewins's, but it wouldn't be far off. Ewins could have done some sweet skysurfer designs, but the flow of the action would never have matched Kennedy's Midnight Surfer. A Ewins version of The Taxidermist would not have been at the races at all, I reckon. Kennedy's mixture of humour and pathos is perfect as was also demonstrated in stories like Two Ton Tony Tubbs, and Kenny Who?.
In summary, Cam Kennedy is my pick here.