maria plays at her best more often than serena plays at hers, but if both are at their peak best, give serena the edge. maria is still improving we haven't seen her very best yet.
um, did you watch tennis from 1999-2003? Serena's tennis from that period (you can subtract out most of 2000 though) was better than Maria EVER. Serena has played superb tennis WAY more times in her career than Maria so far. Maria will never he the athlete or the dominating force on the tour like Serena. Serena's best is better than anyone's. Maria's best isn't better than Venus or Serena's best tennis, period.