none of them have sound thats described as great , very few flatscreen tvs do ...
the latest panasonic plasmas are the best , at 42in anyway , and at any size imo , and according to the majority of reviews ...
either the 42g20 or 42v20 , its possible the v20 may have slightly better sound , im not sure , but i wouldnt think it would be much better , if at all , either tv is a fantastic set , the v20 being slightly better with picture quality , slightly better blacks , but not much between them really , according to reviews ..
edit .. actually panasonic are the only makers of 42in plasmas right now afaik....