easy question, quality over quantity. the question is extremely easy if you're talking purely 'top 20' versus 'bottom 80' in terms of ratings/quality because generally speaking great indies or great big Triple A games are going to have honest ratings. So you'd get a Bioshock and/or something like smaller like a Binding of Issac sort of game
now if you were to change your question to 'top 20 best selling games' versus the next '80 best sellers underneath' then that becomes a very interesting question for the simple fact that sometimes awesome games sell well and sometimes less awesome games also sell well (COD). I think a good sales versus bad sales quality vs quantity question would be more interesting because great sales doesn't necessarily gurantee anything
top 20 ver next 80 is just too easy, you would be sacraficing playing all time classics if you didn't pick top 20
