personaly Overclocked but thats just because i have already finnished assassins creed. (which was excelent btw although a little repetative between major assassinations). overclocked hasnt really grabbed my fancy though tbh although it sounds interesting. just check out reviews on both games and work out which one is more up your street.
Thanks. I was swaying towards Assassins Creed as it has a great write up...but my pal suggested Overlocked; I can't afford the two of them at the mo unless I go without food for a week lol.