February’s variant cover theme fro DC Comics will be HArley Quinn, and that should come as zero surprise. It worked for Marvel with Deadpool, a similarly anarchic fourth-wall busting character. In fact if Marvel and DC were to do a crossover, I think Deadpool vs Harley would be the Batman vs Spider-man of the day.
In addition, Harley’s new, Suicide-Girls-inspired look has definitely caught on, supplanting the sturdily iconic Bruce Timm designed onesie. I don’t know who did the deredisgn for the New 52, but I think it may have been the most successful of the bunch.