  Nine of the most important estimators known for the two-point correlation
function are compared using a predetermined, rigorous criterion. The indicators
were extracted from over 500 subsamples of the Virgo Hubble Volume simulation
cluster catalog. The ``real'' correlation function was determined from the full
survey in a 3000Mpc/h periodic cube. The estimators were ranked by the
cumulative probability of returning a value within a certain tolerance of the
real correlation function. This criterion takes into account bias and variance,
and it is independent of the possibly non-Gaussian nature of the error
statistics. As a result for astrophysical applications a clear recommendation
has emerged: the Landy & Szalay (1993) estimator, in its original or grid
version Szapudi & Szalay (1998), are preferred in comparison to the other
indicators examined, with a performance almost indistinguishable from the
Hamilton (1993) estimator.
