Given two biased estimators MOP and Hill, the asymptotic root efficiency (AREFF) of MOP relatively to Hill is given in Brilhante et al. (2013). Note that highest the AREFF indicator the better is the MOP estimator.
References
Brilhante, M.F., Gomes, M.I. and Pestana, D. (2013). A simple generalisation of the Hill estimator.
Computational Statistics and Data Analysis, 57, 518-- 535.