Really depends. SC-55 excels at games made for GS and GM. But games that use LA or XG will sound terrible on it.
If we are sticking with basic GS/GM, SC-88 Pro is superior to the 55 in just about every way (unless you really need capital tone fallback).
For myself, depends on the game, but MU2000 + PLG150-DR always gives me a massive boner. 😀
CM-64, CM-500, SC-55MkII, SC-88 Pro, SY22, TG100, MU2000EX, PLG100-SG, PLG150-DR, PLG150-AN, SG01k, NS5R, GZ-50M, SN-U110-07, SN-U110-10, Pocket Studio 5, DreamBlaster S2, X2, McFly, E-Wave, QWave, CrystalBlaster C2, Yucatan FX, BeepBlaster, SuperOctet!