Several low power and high speed 4:2 compressor designs of various digital logic styles are studied in this paper. HSPICE simulation results are provided giving a clear picture of the performance of these circuits in terms of power dissipation and delay. To carry out the analysis, a methodology for proper power measurement of pass-logic circuits has been developed and is presented. Finally, recommendations are made as per which circuits are most suitable depending on the needs of the system in which they will be implemented.